REVIEW

Risk Perceptions Related to SARS and Avian Influenza:Theoretical Foundations of Current Empirical Research

Anja Leppin & Arja R. Aro

Published online: 12 February 2009# International Society of Behavioral Medicine 2009

AbstractBackground The outbreak of severe acute respiratorysyndrome in 2003 and the subsequent emergence of theH5N1 virus have highlighted the threat of a globalpandemic influenza outbreak. Planning effective publichealth control measures for such a case will be highlydependent on sound theory-based research on how peopleperceive the risks involved in such an event.Purpose The present article aims to review theoreticalmodels and concepts underlying current empirical researchon pandemic influenza risk perception.Method A review was conducted based on 28 empiricalstudies from 30 articles which were published between2003 and 2007.Results Concepts of risk perception mostly seemed morepragmatic than theory-based and were highly heteroge-neous, for instance, in terms of conceptualizing riskperception as an exclusively cognitive or as a cognitiveand emotional phenomenon or whether the concept wasdominated by expectancy or expectancy and value compo-nents. Similarly, the majority of studies investigating riskperceptions and protective behaviors were not model-based.Conclusions The current body of knowledge can onlyprovide preliminary insights. Unlike the reviewed studies,which were mostly launched as a rapid response to outbreaksituations, future research will have to invest more stronglyinto theoretical work to provide sounder evidence.

Keywords Severe acute respiratory syndrome (SARS) .

Avian influenza . Risk perception . Theory .Models

Introduction

Newly emerging respiratory infectious diseases like severeacute respiratory syndrome (SARS) and avian influenzahave created novel challenges to traditional nonmedicalpublic health containment strategies [1]. In the initialabsence of effective vaccination, measures such as quaran-tine, travel restrictions, and the promotion of individualprotection behaviors such as frequent hand washing,wearing of face masks, or avoiding public gatherings werethe measures of choice during the SARS outbreak and willbe again should another pandemic influenza, caused, forinstance, by H5N1, occur. The effectiveness of such controlmeasures depends fundamentally on the public’s willing-ness to cooperate, which again is likely to be associatedwith the level of personal risk people perceive. Soundempirical data about the ways lay persons perceive suchrisks are therefore essential to develop health communica-tion strategies and successfully devise containment plans.Collecting such a sound database, however, requires first athorough theoretical understanding of what constitutes laypersons’ risk perceptions of pandemic influenza, how theseperceptions emerge, as well as how they influence protectivebehaviors.

Therefore, as an addition to this special issue’s originalcontributions on perceptions of SARS and avian influenzarisk, the present article will take a more general perspectiveand explore the theoretical foundations of risk perceptionresearch within the specific context of pandemic influenza1.Specifically, the present article aims to review theoreticalmodels and concepts underlying empirical research on

Int. J. Behav. Med. (2009) 16:7–29DOI 10.1007/s12529-008-9002-8

A. Leppin (*) :A. R. AroUniversity of Southern Denmark, Institute of Public Health,Unit for Health Promotion,Niels Bohrs Vej 9,6700 Esbjerg, Denmarke-mail: aleppin@health.sdu.dk

1 The term pandemic influenza will be used as a generic term for life-threatening respiratory infectious diseases with epidemic–pandemicpotential, of which SARS and H5NI are only two examples, whichmight be succeeded by further outbreaks of other viruses.

perceptions related to SARS and avian influenza as the twomost recent threatening cases of respiratory virus outbreaks.The particular focus of this review will be on how riskperception is conceptualized and also on which modelshave been chosen by current empirical studies to test for therelationship between SARS or avian influenza risk percep-tion and protective behaviors.

Current Concepts of Risk Perception

The Psychometric Paradigm and Expectancy-Value Models

Concepts of risk have been shaped in the light of differentscientific traditions and paradigms. Psychological researchon risk perception has mainly been dominated by thepsychometric paradigm on the one hand and the subjectiveexpected utility approach on the other [2]. The psychomet-ric paradigm [3, 4], wanting to investigate what character-izes risk in the public’s view, has tried to map lay people’sperception of different types of hazards in factorial space,describing the decisive dimensions as unknown risk anddread risk, with the latter dimension being the mostimportant determinant of a “risk image.” While unknownrisk describes phenomena which are perceived of as new,nonobservable, unknown to science, and whose effects aredelayed, dread risk has been defined by characteristics suchas involuntariness, uncontrollability, fatal consequences,and catastrophic dimensions. Technological hazards, suchas nuclear power or genetically modified food, tend to beperceived of as unknown risks and, just like naturaldisasters, often convey high dread potential. Lifestylebehaviors like smoking, unhealthy eating habits, or carspeeding, on the other hand, are usually thought of asobservable and well known and thus rank relatively low onthe factor unknown risk. Also, lay persons tend to perceivethese behaviors as voluntary, controllable, and as affectingpeople one at a time rather than simultaneously endanger-ing whole populations. So, in the public’s eye lifestylefactors lack the dread potential of technological risks andhence often seem more acceptable than the former.

While there is yet no empirical evidence for this, onemight speculate that the specific characteristics of diseasethreats such as SARS or avian influenza would place themconceptually closer to technological risks or to naturaldisasters than to individual risk behaviors. Just as fortechnological risks, an initial lack of knowledge about theorigin or the life course of a newly emerging virus and thefact that the infection process in itself is unobservable andthat visible effects are delayed might produce high rankingson the factor unknown risk. In addition, pandemic influen-za, just like technological and natural hazards, hascatastrophic potential, as infection could be fatal, and large

numbers of people would be affected at the same timewithin the same geographical region. Beyond this, globalmobility is bound to further add to catastrophic impact byrapid spread of a respiratory virus to distant regions of theworld. Also, as specific vaccines need time to be developedand as 100% effective medication is unlikely to be availablefor a considerable time span, these diseases are difficult tocontrol - all aspects which suggest that pandemic influenzawould rank high on the dread risk factor just liketechnological risks or natural disasters. On the other hand,it is particularly the issue of control which might makeperceptions of pandemic influenza more ambiguous. Likein the case of natural disasters or technological hazards,there is an outside threat, in this case a virus, which mightseem difficult to control. However - different from naturalor technological hazards - this particular outside agentdepends on everyday human behavior to spread, i.e., socialcontact and hygiene behaviors. Even more than for instancesmoking, car speeding, or alcohol consumption, thesebehaviors are extremely common, well known, and observ-able, more or less voluntary and—at least theoretically—modifiable or controllable. Objects with these character-istics are rarely perceived as “high risk” by lay persons, asresearch based on the psychometric paradigm has demon-strated [4]. Thus, at least during the initial phase of anoutbreak, there might be a difference between perceivedthreat of the disease and the risk potential actuallyattributed to one’s own individual contact behaviors.

This notion needs empirical testing, just as the assump-tion that the aggregate-level data of the psychometricparadigm are transferable to the individual level. If provenvalid, however, this phenomenon might have consequencesfor planning public health control strategies. To combatdisease spread in the initial phases of a pandemic influenzaoutbreak, where no vaccine is available, control measureswill have to rely on influencing the extent (e.g., avoidingpublic gatherings, closing down schools and work places)and mode (e.g., wearing of face masks, no handshaking,frequent hand washing with soap, etc.) of human contactbehaviors. Thus, within a very short time span, socialinteraction would have to transform from an integral,essential, mostly beneficial, or at least unquestioned partof daily life into risk-fraught, even potentially lethalbehavior. How prepared or reluctant people are to makethat mental shift, how effective risk perceptions are ininitiating protective behaviors without creating panic andproblematic social exclusion processes, and which factorsinfluence these processes are key questions for planningcontainment and communication strategies.

Unlike the psychometric paradigm, which has beendeveloped to describe and investigate aggregate-levelcharacteristics of various types of hazards perceived of as“low risk” or “high risk,” expectancy-value models have

8 Int. J. Behav. Med. (2009) 16:7–29

focused on how individual risk perception influencesdecision making and behavior. Based on the subjectiveexpected utility (SEU) approach [2], which posited thatpeople’s choices are a product of assessments of probabilityand utility/desirability of options, health-related approachessuch as the Health Belief Model (HBM) [5, 6] or ProtectionMotivation Theory (PMT) [7, 8] have defined risk in linewith the technical understanding of risk, i.e., as thelikelihood of contracting a disease multiplied by diseaseseverity. Together with other types of expectancies, likeoutcome expectancies (or cost–benefit perceptions) andself-efficacy expectations, these perceptions of risk are thenpresumed to determine health-protective behaviors such asusing health care services, refraining from smoking, orbeing physically active. These models have found wide-spread application as well as a considerable degree ofempirical support (see below) and might therefore alsoprovide a sound basis for answering questions on how farpandemic influenza risk perceptions can be relied upon asmotivating factors for protective behaviors. Beyond a merefocus on risk perception, they can also help reveal howother types of cognition, such as outcome expectancies,about control measures as well as judgements on costsinvolved in such measures, such as cutting or reducinghuman contacts, might support or counteract the motiva-tional processes initiated by risk perception.

Risk as Cognition or Risk as Emotion?

The Health Belief Model and Protection MotivationTheory, however, also have shortcomings which couldlimit their use for studying pandemic influenza riskperception. One common criticism of these models pertainsto their strong focus on conscious-rationalist situationalappraisal which falls short of capturing the emotionalprocesses involved in human decision making. Dual-process models have for a long time been suggesting thatanalytic-central and emotional-heuristic processes work inconcert to select and prioritize decisions and behavioralreactions [9, 10], and under certain circumstances emotionsmay even be the dominant force. Damasio [11] has thussuggested that automated incentive or alarm signals linkedto pleasant or unpleasant “gut feelings” often precedecognitive reasoning. In a similar vein, processing theorieshave emphasized the importance of an emotion–cognitionpathway [12–14]. Based on these ideas, the “risk asfeelings” or “risk as values” approach [15–17], just as thenotion of an “affect heuristic” [18, 19], have posited thatwhen making judgements individuals draw on two process-es of evaluation, which reside in two distinct, if interrelated,systems of decision making. These are an analytic-rationalsystem based on logical reasoning and probability judge-ments, on the one hand, and an experiential system, on the

other, where direct automatic visceral reactions influencedecision making, based on images, metaphors, and relatedemotions.

While the HBM or PMT, unlike the original SEUapproach, do include an emotional component, i.e., fear,they represent a cognitive appraisal framework [20, 21] inassuming that it is mostly cognitions which give raise toemotions, i.e., cognitive risk assessment determines experi-ence of fear. This framework might well apply for behaviorsaimed at fending off long-term chronic disease such asscreening participation or lifestyle behaviors. In such cases,fear is likely to be less imminent and therefore secondary tomore rational reflections about gains and losses related toprotective behavior. However, in an acute threat situationlike an influenza pandemic, emotional aspects might gainmore immediate importance. This is all the more likely if,during the early stages of an outbreak, experts are unable tomake more than tentative statements and provide partlycontradictory prognoses and recommendations as it hap-pened with SARS. Under these circumstances cognitiverisk assessments might be severely hampered by lack ofevidence-based information. Consequently, individualsmight have little choice but to rely on experiential judge-ment. However, what role exactly an affect- or emotion-based judgement plays in interaction with risk-relatedcognitions is still an issue in need of clarification.

The Social Context of Risk Perception

Another issue which warrants more attention than it has sofar received in risk perception research is the social contextof risk perception. Health behavior models such as theHBM or PMT have mainly focused on how risk perceptionsand other cognitions influence behavior, while the questionof how risk perceptions are formed in the first place has metwith little attention. Public risk perception is thus mostlyconceived of as an aggregate of purely individual assess-ments - a perspective which neglects cultural and subcul-tural frames of reference [22]. Slovic [4], in contrast, hasemphasized the importance of worldviews, which can beperceived of as sociocultural attitudes guiding individualrisk perception by providing normative orientation. Simi-larly, social representation theory [23] or the socialamplification of risk framework [24, 25] have emphasizedthe importance of collective, (sub)cultural–social dynamicswhich shape individual ways to perceive of and react torisk.

Even more than other types of diseases, infectionsinherently involve a social dimension due to the socialbasis of transmission. Risk perception here pertains notonly to the self but also to the likelihood of close othersbeing affected. Beyond that, the possibility that oneselfmight become instrumental in infecting others can evoke

Int. J. Behav. Med. (2009) 16:7–29 99

anticipations of guilt and blame. Furthermore, anticipationof social exclusion processes affecting those who havebecome “cases” or those who are facing the frontlinecombating disease, like health care workers, are bound tobecome a part of pandemic influenza risk conception andtherefore might also have an influence on risk-relatedbehaviors. While such processes can be assumed to berelevant for all societies, it seems probable that such “socialrisk perceptions” are even stronger in the collectivistsocieties of Asia than in the more individualist cultures ofthe West. Factoring in such processes of perceiving andreacting to collective threat is unquestionably an essentialelement of pandemic influenza preparedness.

Models of the Risk Perception–Behavior Relationship

In line with the SEU approach, health behavior modelsassume that high perceived personal risk can be expected tomotivate people into action. However, it has also beenpointed out that not all empirical studies which have testedthis assumption have yielded particularly large effects orhave borne out this type of effect at all [26, 27]. Thisheterogeneous state of empirical findings reflects conflictingunderlying psychological processes, but also methodologicalproblems involved in the respective studies.

In terms of psychological processes, one explanation forthe diversity of findings is that very high risk perceptions insome population subgroups, instead of mobilizing peopleinto action, might evoke feelings of helplessness whichcould paralyze rather than provoke protective behaviors. Athreat like pandemic influenza, where in the initial absenceof a vaccine the efficacy of countermeasures must remainunclear, might be particularly prone to such no-actionresponses. Vice versa, some people will downplay risk as akind of coping strategy and thus report lower riskperception which, however, would not necessarily keepthem from initiating protective action. Testing such alter-native pathways requires the investigation not only ofcognitive but also of emotional aspects of or reactions torisk perception.

Also, risk perceptions are not alone in determiningprotective behaviors. In the absence of positive outcomeexpectancies for protective behaviors or high self-efficacy,in terms of feeling able to perform these behaviors, highrisk perceptions are unlikely to be particularly effective.Another important factor in this context is perceived socialnorms as outlined by the Theory of Reasoned Action/Theory of Planned Behavior [28, 29]. Normative influencescan explain why even those with low personal riskperceptions sometimes adopt protective behaviors. Duringan outbreak protective behaviors are widely recommendedand visibly performed by a great number of people, so that

their practice acquires normative status. During the SARSepidemic this might have happened with behaviors such aswearing of face masks, frequent hand washing, or avoid-ance of public gatherings, where the issue was not only toprotect oneself but also to not be perceived as someone whoputs others at risk.

Brown [30] has pointed out yet another reasoningprocess which might cancel out any protective motivationalimpulses of risk appraisal: Belief modification as a meansto reduce cognitive dissonance. In a prospective study oncar speeding the author found an inverse relationshipbetween car speeding and perception of accident risk,which he accordingly interpreted as an attempt to reducedissonance or else as a learning effect signaling that, in theabsence of (immediate) negative consequences, risk per-ceptions might decrease [31]. For pandemic influenza suchan effect could occur if people who escape infection duringan initial wave get careless, based on the assumption thatthey could be “immune.” Finding out whether suchprocesses actually take place requires longitudinal processapproaches and also in-depth explorations of people’s waysof reasoning about their personal risk perceptions.

Finally, the impact of risk perceptions on behavior islikely to differ depending on the specificity of the riskassessments. Thus, perceived general risk of contractingSARS or avian influenza might relate less strongly tospecific types of protective behavior such as not shakinghands, frequently washing hands, etc. than the morespecific risks perceived as being involved in these particularbehaviors.

From a methodological perspective, Brewer et al. [26](see also [27]) have recently highlighted another series ofproblems. One of these is the failure to condition the riskquestion on not taking action [27]. Not accounting foranticipated or intended positive behavior change can lead toan underestimation of risk because it is likely that somepeople assess their risk as being low due to alreadyfactoring in a change towards anticipated or alreadyaccomplished protective behavior. The authors, however,also pointed out that the relevance of this issue depends onwhether the precaution is actually expected to eliminate orat least reduce the risk (response efficacy). For investigatingpandemic influenza, this type of validity threat mighttherefore be less imminent than, e.g., for a study on therelationship between perceived risk of “normal” influenzaand getting a vaccination. Even so, such effects are unlikelyto be nonexistent, so that perceived pandemic influenza riskresearch should also profit from assessments with andwithout (anticipated or actual) behavior change.

Interpretational ambiguity can, of course, also resultfrom temporal relations between variables. In cross-sec-tional studies perceptions of risk for “ordinary influenza” inpeople who have already been vaccinated are bound to be

10 Int. J. Behav. Med. (2009) 16:7–29

affected by their expectation of being protected by thevaccination, hence their lowered risk perceptions - whichthen should not be interpreted as an indication of higherrisk perception leading to less protective behavior. Breweret al. [26] explicitly tried to disentangle the various types ofeffects by investigating different temporal hypotheses ofrisk perception about Lyme disease and protective behavior,i.e., getting vaccinated. Based on their findings, they oncemore emphasized the well-known predicament of cross-sectional studies. Even though often claiming to test abehavior motivation hypothesis, studies based on correla-tional designs cannot perform more than a test of anaccuracy hypothesis, stating that people who engage inmore risk behaviors should also endorse higher riskperceptions. Testing a behavior motivation hypothesis onthe other hand requires a longitudinal design, looking atwhether higher risk perception at t1 leads to a strongerincrease in protective behavior at t2. Yet another effect issuggested by the risk appraisal hypothesis, which suggeststhat risk appraisal will change as a result of behaviorchange, i.e., it will decrease once positive behavior changehas been initiated. The two tests should thus generateinverse correlations. In the first phase, when the behaviormotivation model is tested, perceived risk should bepositively related to preventive behavior. In the secondphase, however, when the risk appraisal model is underinvestigation, a negative relationship between preventivebehavior and risk perception should be expected. Empiricalfindings of the Brewer et al. [26] study supported theseassumptions, showing that higher initial risk judgementsconcerning Lyme disease encouraged people in favor ofvaccination. Taking action subsequently reduced riskperception, indicating also that people who had beenvaccinated viewed their risk as lower than those who hadnot, thereby confirming the accuracy hypothesis. The quitecommon failure to explicitly distinguish these processescontributes to misinterpretation of findings and misattribu-tion of effects.

The long list of open questions and unsolved issues inrisk perception research certainly sets an ambitiousresearch agenda. The purpose of the present study istherefore, first, to take stock of the status quo with regardto the area of pandemic influenza risk, i.e., to investigatethe theoretical basis of current empirical research onSARS and avian influenza risk perceptions. Relevantempirical studies will be explored in terms of (1) theirconceptual and operational definitions of risk perceptionand (2) the theoretical models used for investigating therole of risk perceptions as determinants of protectivebehaviors. The review uses a descriptive–quantitativeapproach insofar as it not only tries to describe thedifferent concepts and models of risk used in the variousstudies and also to quantify the amount of studies falling

into different categories in order to give a more preciseaccount of the state of theoretical groundwork behindcurrent empirical risk perception research. What thepaper does not provide is a review on empirical findingsof the current risk perception research itself in termsof degree of risk perception in different populations,or strength of the risk perception–health behaviorrelationship.

Method

The analysis is based on 28 empirical studies from 30publications2 focusing on the threat posed by SARS andavian influenza and the subjective perceptions related tothese health hazards (see Table 1). The search for studiespublished between January of 2003, the year of the SARSoutbreak, and October 2007 was conducted with the help ofdifferent databases (PUBMED, EMBASE, PSYCLIT, andCINAHL), alternatively combining the term “risk percep-tion” with “SARS,” “avian flu,” “avian influenza,” and“pandemic influenza.” Additionally, reference sections ofthe papers obtained were searched for further articles. Astudy was included only if it explicitly referred to “riskperception” or else to subcomponents of the perceived riskconcept, i.e., “perceived susceptibility” or “perceivedvulnerability.” Thus, studies dealing exclusively with, forinstance, SARS-related “distress” or “threat” withoutexplicitly referring to the perceived risk concept were notincluded in the review.

Categorization Procedures

Exploring risk concepts was made difficult by the factthat the large majority of studies provided no explicittheoretical definition of how risk perception wasconceived of. As a consequence, risk concepts had tobe traced back to and deduced from the operationalmeasures used. Descriptions of these assessments, how-ever, were not always sufficiently comprehensive orparticularly precise, and the terminology used in theintroductory or discussion sections of the articles werenot always consistent with the measures actually appliedand/or compatible with conventional definitions, all ofwhich contributed to the complexity of the classificationprocedure. This multifaceted picture was further com-plicated by the fact that many studies, besides explicitlyintroducing measures of risk perception, additionallyassessed aspects which could be considered as risk-

2 In two cases, publications clearly seemed to be based on the samestudy. These were therefore counted as one study each; however, inboth cases, for the information in Table 1, all four articles were used.

Int. J. Behav. Med. (2009) 16:7–29 1111

Tab

le1

Overview

ofcharacteristicsof

thereview

edstud

ies

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Abbateet

al.

[50]

Avian

influenza

Italy

Poultryworkers,

aged

19–75,

from

110poultry

farm

sin

the

Cam

pania

region,Italy;

N=257

Cross-sectio

nal

interview

survey

intheworkplace,

Decem

ber2005–

March

2006

Evaluationof

know

ledge,

attitudes,andinfection

controlpractices

None

CognitiveDim

ension

CognitiveDim

ension

Yes

Universal/Com

munity

risk

Universal/Com

munity

risk

Modificationof

work

habits;Protection

measures,e.g.

wearing

gloves,face

masks,eye

protectio

n,hand

washing

Perceived

risk

forcontractingavianinfluenzafor:

poultryworkers,butchers,veterinarians,hunters

Perceived

severity:A1isa

seriousdisease

Dichotomousscale:

yes–no

Three-point

scale:“agree,”

“uncertain,”and“disagree”

Emotional

Dim

ension

Emotional

Dim

ension

Personalrisk

Networkrisk

Fearof

getting

avianinfluenza

Fearof

family

–cow

orkers

getting

avianinfluenza

Ten-point

scale:

“nofear

atall”

to“verymuchfear”

Barenneset

al.[80]

Avian

influenza

Laos

Three

random

samples

Cross-sectio

nal

interview

survey,

April–

March

2006

Tolearnmoreabout

Laotian’sknow

ledgeof

HPA

1andperceptio

nsof

theirrisk

None

CognitiveDim

ension

Yes

Universal/Com

munity

risk

Protectivebehaviors,

e.g.,maskwearing,

hand

washing

(1)Market

vendorsand

visitors

inan

urbansetting,

meanage=

41;

N=461

Perceived

risk

foravianinfluenzaat

home

Perceived

risk

foravianinfluenzain

Laos

(2)Peopleliv

ing

inasemiurban

setting,mean

age=

34;N=192

Dichotomousscales:yes–no

(3)Peopleliv

ing

inaruralsetting,

meanage=

38;

N=189

Brug

etal.

[44]

SARS

Netherlands

Participantsin

aninternet

research

panel,aged

19–78;

N=373

Cross-sectio

nal

internet

survey,

during

outbreak

2003

inan

area

with

nocases

ToexploreSARS-related

perceptio

ns,know

ledge,

actio

ns,anduseof

inform

ationsources

Precaution

Adoption

Model

CognitiveDim

ension

Yes

Personalrisk

Protectivebehaviors,

e.g.,wearing

offace

masks,hand

washing

Perceived

likelihoodof

acquiringSARS

Perceived

likelihoodof

acquiringSARScomparedto

otherpersons

Perceived

likelihoodof

otherdiseases

(e.g.,cancer/

accidents)

Perceived

likelihoodof

dyingfrom

SARS

Five-pointscales:“neglig

ible”to

“verylarge”

Emotional

Dim

ension

Personalrisk

Worry

aboutoneselfcontractingSARS

Networkrisk

Worry

aboutafamily

mem

bercontractingSARS

Universal/Com

munity

risk

Worry

aboutSARSoccurringin

theregion

Worry

aboutSARSem

erging

asahealth

issue

Five-pointscales:“neglig

ible”to

“verylarge”

Cavaet

al.

[32]

SARS

Canada

Men

andwom

enwho

hadbeen

quarantined

durin

gthe

outbreak;one

third

=healthcare

workers;N

=21

Qualitativestudywith

asemistructured

interview

guide

database,October

2003–M

arch

2004

Toexploretheexperience

ofbeingquarantin

ed,

particularly

the

relatio

nshipbetween

perceivedrisk

and

compliancewith

the

quarantin

eorder

Health

Belief

Model

and

Protection

Motivation

Theory

Nostandardized

questio

ns;narratives

Emotional

Dim

ension

Yes

Top

icsRaised

Fearanddenial

with

regard

toSARS

Com

pliancewith

quarantin

emeasures

Beliefs

aboutlevelof

risk

ofcontractingSARS

Beliefs

aboutlevelof

risk

ofspreadingSARS

12 Int. J. Behav. Med. (2009) 16:7–29

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Chang

etal.

[57]

SARS

Taiwan

Nursesfrom

one

hospital,aged

29–41;N=330

Cross-sectio

nal

questio

nnaire

survey,

July–A

ugust2003

Totestthehypothesisthat

susceptibility

perceptions

moderatetherelationship

betweenorganizational

commitm

entand

intentionto

leavethe

profession

Noneforthe

risk

concept

CognitiveDim

ension

Yes

Personalrisk

Behavioralintention,

i.e.,intentionto

quit

riskyjob

Infectionprobability

dueto

job:

bytaking

care

ofa

SARSpatient,Imight

becomeinfected

Five-pointscale:“stronglyagree”

to“stronglydisagree”

Chong

etal.

[34]

SARS

Taiwan

Health

care

workers

from

alargetertiary

hospitalin

Southern

Taiwan,aged

21–59;

N=1,310

Cross-sectio

nal

questio

nnaire

survey,

partpaper–pencil,

partinternet-based,

earlyMay

(initial

phase)–June2003

(repairphase)

Toassess

theim

mediate

stress

andpsychological

impact

ofSARSon

health

workers

ina

tertiary

hospitalwhich

was

seriouslyaffected

byan

outbreak

and

compare

data

over

aperiod

of6weeks

None

CognitiveDim

ension

No

Personalrisk

Perceived

risk

throughjob:

myjobputsmeatgreatrisk

forexposure

toSARS

Perceived

fatality:

little

chance

ofsurvival

ifinfected

Emotional

Dim

ension

Personalrisk

Fearof

falling

illwith

SARS

SocialAspects

Fearof

passingSARSto

others

Fam

ily/friends

worried

that

they

might

beinfected

byme

Peopleavoidfamily

becauseof

work

RiskAcceptance

Accepttherisk

aspartof

job

Other

Social–CognitiveCon

structs

Personalcontrolover

infection

Intentionto

change

job

Five-pointscales:“stronglyagree”

to“strongly

disagree”

deZwartet

al.[40]

Avian

influenza

Multicountry

comparison

study:

five

European

countriesand

threeAsian

countries/

cities:

Denmark,

Netherlands,

UK,Spain,

China,Hong

Kong,

Singapore

Eight

random

samples;adult

populatio

nin

the

respectiv

ecountries,aged

18–75;

N=3436

Cross-sectio

nal

telephonesurvey,

September–

Novem

ber2005

Investigationof

risk

perceptio

nandefficacy

beliefs

relatedto

avian

influenza

Protection

Motivation

Theory

CognitiveDim

ension

No

Personalrisk

Vulnerabilityto

SARS:perceivedlik

elihoodof

becominginfected

Perceived

severity

ofSARS:risk

ofdyingfrom

SARS

Risk:

multip

licationof

vulnerability

andseverity

asspecifiedby

protectio

nmotivationtheory

Five-pointscale:

“low

”to

“high”

Fieldingetal.

[43]

Avian

influenza

HongKong

Random

sample;

general

populatio

nhouseholds,

aged

16–95;

N=986

Cross-sectio

nal

telephonesurvey,

during

thepeak

ofoutbreak

2004

Todeterm

inepopulatio

nknow

ledgeof

risk

and

self-protectionpractices

andestim

atepopulatio

nexposure

from

live

chickensales

None

CognitiveDim

ension

Yes

Personalrisk

Protective/risk

behavior,e.g.,

buying

livechickens,

handlin

gchickens

Perceived

likelihoodof

getting

sick

from

buying

live

chickens

Five-pointscale:

“never–very”

to“unlikely”

and0–

100%

probability

estim

ate

Universal/Com

munity

risk

Buyingliv

echickens

isriskyto

health

Emotional

Dim

ension

Networkrisk

Friends

expressing

worry

aboutcatching

avian

influenza

Five-

toseven-pointscales

Int. J. Behav. Med. (2009) 16:7–29 1313

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Hongand

Collin

s[53]

SARSand

influenza

Korea

Adults

from

the

generalpublic,

aged

20to

75,

who

were

approached

atrandom

inthe

city

center

and

shopping

malls;

N=350

Cross-sectio

nal

questio

nnaire

survey,

October

2003

Toexam

inehow

connectio

nsbetween

risk

perceptio

nsof

influenzaandSARS

affect

behavioral

intentions

for

vaccination

State-

dependent

expected

utility

fram

ework

CognitiveDim

ension

Yes

Universal/Com

munity

risk

Behavioralintention

forinfluenza

vaccination

Perceived

riskinessof

SARS

Perceived

riskinessof

“normal”influenza

Five-pointscales:“not

atallrisky

”to

“extremelyrisky”

Imai

etal.

[35]

SARS

Japan

Health

care

workers

from

sevenhospitals

throughout

Japan,

meanage

35.6

(SD=11.2);

N=7,463

Cross-sectio

nal

questio

nnaire

survey,

immediately

after

SARSepidem

icin

otherAsian

countries

in2003

Toexam

inethelevelof

SARSrisk

perceptio

nandanxietyin

Japan,

the

know

ledgeof

preventiv

emeasuresandperceptio

nof

infectioncontrol

measuresandrelatio

nsam

ongthesefactors

None

Emotional

Dim

ension

No

Personalrisk

Fearof

falling

illwith

SARS

RiskAcceptance

Riskaccepted

aspartof

job

Other

Social–CognitiveCon

structs

Personalcontrolover

infection

Intentionto

change

job

Avoidance

ofpatients

Seven-point

scales:“stronglydisagree”to

“strongly

agree,”+“donotknow

”

Jiet

al.[42]

SARS

(1)Toronto,

Canada

University

students,N=104

(Chinese

background),

N=35

(Canadians

ofEuropean

descent)

Cross-sectio

nal

questio

nnaire

survey,

May–June2003

TotestifChinese

students

aremoreunrealistically

optim

istic

than

European-Canadian

students

Theoryof

Optim

istic

Bias/

Unrealistic

Optim

ism

CognitiveDim

ension

No

Personalrisk

(2)Beijin

g,China

Perceived

probability

ofcontractingSARS

Probabilityof

ownchance

tobecomeinfected

ascomparedto

anaverageperson

ofsamegender

and

age

Universal/Com

munity

risk

Perceived

probability

that

anaverageperson

ofsame

ageandgender

might

getinfected

Five-pointscales:“m

uchless

likelythan

average”

to“m

uchmorelik

elythan

average”

Koh

etal.

[54]

SARS

Singapore

Allem

ployeesof

nine

major

health

care

institu

tions;

N=10,511

Cross-sectio

nalmailed

questio

nnaire

survey,

during

outbreak,

March–June2003

Learningaboutthefears,

anxieties,andreactio

nsof

health

care

workers

during

theSARS

epidem

ic

None

CognitiveDim

ension

SocialAspects

No

Personalrisk

Close

others

worried

they

might

beinfected

byme

Perceived

risk

throughjob:

jobputsmeat

greatrisk

ofexposure

toSARS

Fearof

spreadingthe

disease

Emotional

Dim

ension

Socialavoidancebecause

ofjob

Personalrisk

Six-point

scales:“strongly

disagree”to

“strongly

agree”

Fearof

falling

illwith

SARS

Riskacceptance

Riskaccepted

aspartof

job

Six-point

scales:“stronglydisagree”to

“strongly

agree”

Koh

etal.

[55]

SARS

(1)Singapore

Health

care

workers

from

(1)nine

prim

ary

hospitalsand

Cross-sectio

nal

questio

nnaire

survey,

May–S

eptember

2003

Study

ofperceptio

nsof

risk

forSARSinfection

andpreventiv

emeasures

amonghealth

care

None

CognitiveDim

ension

No

Personalrisk

Perceived

risk

throughjob:

jobputsmeatgreatriskfor

exposure

toSARS

14 Int. J. Behav. Med. (2009) 16:7–29

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

nine

major

institu

tional

health

care

settingsin

Singapore;

N=15,025

workers

inSingapore,

who

handledcasesof

SARSandin

Japan,

aSARS-freecountry

Emotional

Dim

ension

Personalrisk

Fearof

falling

illwith

SARS

(2)Japan

(2)Seven

tertiary-

levelhospitals

throughout

Japan;

N=9,978

Six-point

scales:“stronglydisagree”to

“strongly

agree”

Kristiansen

etal.[47]

Avian

influenza

Norway

(1)Norwegians

aged

15–67;

N=1,004

Cross-sectio

nal

internet-based

questio

nnaire

survey

Whatarepeople’s

perceptio

nsof

the

mortalityrisk

during

aninfluenzapandem

ic?

None

CognitiveDim

ension

No

(2)Norwegians

aged

68+,all

random

lychosen

from

aninternet-based

panelof

25,000

Norwegians

aged

15years+;

N=165

Universal/Com

munity

risk

Perceived

probability

ofdeathfrom

AI:estim

ated

numberof

fatalitiesin

Norway

incase

ofan

outbreak

Lau

etal.

[41]

SARS

HongKong

Random

sample;

Chinese-

speaking

residents,aged

18–60;

N=457

Cross-sectio

nal

telephonesurvey,

Decem

ber2003–

January2004

Toinvestigatethegeneral

populatio

n’sperceptio

nson

susceptib

ility

ofcontractingSARSvia

daily

contactswith

asym

ptom

atic

and

recoveredSARSpatients

andthediseases’

consequences

forthe

health

ofrecovered

patients

Health

Belief

Model

CognitiveDim

ension

Emotional

Dim

ension

Yes

Universal/Com

munity

risk

Personalrisk

Avoidance

ofrecoveredpatients

Perceived

susceptib

ility

toSARS

Worry

aboutcontracting

SARSwheninteracting

with

recoveredpatient

Infectivity

ofrecoveredSARSpatients,e.g.,dining

with

recoveredSARSpatient

couldtransm

itSARS

Disturbance

aboutSARS

Perceived

consequences/severity

:mortalityrate

for

SARSpatients;

Consequencesof

SARSforhealth

state

Consequencesof

SARSforability

toperform

job

duties

Dichotomousscales:percentagreem

ent

Lau

etal.

[48]

SARS

HongKong

Travelers

from

mainlandChina

toHongKong,

aged

18–60;

N=839

Cross-sectio

nal

questio

nnaire

survey

conductedin

theexit

hallof

acustom

office

ofamain

border

checkpoint,

April2003

Toinvestigatethe

prevalence

ofpreventiv

ebehaviorspracticed

bycross-border

travelersas

wellasfactorsassociated

with

these

Health

Belief

Model

CognitiveDim

ension

Yes

Personalrisk

Protectivebehaviors,

e.g.,hand

washing,

maskwearing

Perceived

risk

ofcontractingSARS

Universal/Com

munity

risk

Perceived

risk

ofHongKongresidentsto

contract

SARSin

differentprovincesin

mainlandChina

Perceived

fatalityof

SARS

Five-pointscales:“verylow”to

“veryhigh”

Lau

etal.

[51]

SARS

HongKong

Chinese-speaking

residents,aged

15–60,

traveling

back

toHong

Kongby

air;N=

820

Cross-sectio

nal

questio

nnaire

survey

conductedat

airport

expressbusstation

andexpresstrain

platform

atChapLap

Kok

International

Airport,April2003

Toinvestigatefactors

associated

with

SARS-

preventiv

ebehaviors

Health

Belief

model

CognitiveDim

ension

CognitiveDim

ension

Yes

Universal/Com

munity

risk

Universal/Com

munity

risk

Protectivebehaviors,

e.g.,maskwearing,

avoidanceof

public

places

Susceptibility

toSARS:perceivedchance

ofinfection

onboard

Perceived

severity

ofSARS:

Perceived

chance

ofinfectionat

destinationpoint

Perceived

chance

ofmortalityof

SARS

Five-pointscales:“verylow”to

“veryhigh”

Five-pointscales:“very

low”to

“veryhigh”

Int. J. Behav. Med. (2009) 16:7–29 1515

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Lau

etal.

[56]

SARS

HongKong

Ten

random

samples;

Chinese-

speaking

Hong

Kongresidents,

aged

18–60;

Tentelephone

interview

surveys

with

subsequent

cohorts,1–

5before

April2003

(escalatingphase),6

–

10April1andafter

(improvingphase)

Investigationof

the

evolutionandchangesin

attitudes,know

ledge,

andbehaviorsof

Hong

Kongresidentsin

response

tothepublic

health

crisisduring

the

twophases

ofthe

epidem

ic

None

CognitiveDim

ension

CognitiveDim

ension

No

(1)N=80

Personalrisk

Universal/Com

munity

risk

(2)N=156

Susceptibility

toinfectionwith

SARS:perceived

chance

ofinfectionforoneself

Perceived

severity

ofSARS

(IsSARSfatal?)

(3)N=156

Networkrisk

Dichotomousscale:

yes–no

(4)N=91

Perceived

chance

ofinfectionforfamily

mem

bers

(5)N=66

Universal/Com

munity

risk

(6)N=169

Perceived

risk

ofSARStransm

ission

indifferentp

laces

(e.g.,public

transport,office,regions)

(7)N=159

Percent

“verylargeor

large”

(8)N=155

Emotional

Dim

ension

(9)N=165

Personalandnetworkrisk

(10)

N=165

Worry

aboutoneselfandfamily

contractingSARS

Percent

“muchor

very

much”

Leung

etal.

[45]

SARS

HongKong

Fourrandom

samples;adult

Chinese

residents,aged

18+;=N=840

Fourtelephone

surveys,1and1.1:

prosp.

survey,April

2003

andMay–July

2003;2and2.1:

prosp.

survey,May-

July

2003;3:

cross-

sect.survey,May-

June

2003;4:

cross-

sect.survey,Dec.

2003

Toaidplanning

fora

possible

return

ofSARS

or,moregenerally,for

anoutbreak

ofother

infectious

diseases

None

CognitiveDim

ension

Emotional

Dim

ension

Yes

1=N=840

Personalrisk

Personalrisk

Protectivebehaviors,

e.g.,coveringmouths

whensneezing

orcoughing,hand

washing

with

soap,

face

masks,using

serviceutensilsfor

shared

food

1.1=N=480

Perceived

likelihoodof

contractingSARSduring

the

currentoutbreak

General

anxiety(State

Trait

Anxiety

Inventory)

Health

serviceuse

2.0=N=361

Perceived

likelihoodof

survivingSARS,ifinfected

2.1=N=272

Five-pointscales:“veryunlik

ely”

to“verylik

ely”

3.0=N=706

4.0=N=2,574

Leung

etal.

[52]

aSARS

HongKong

Random

sample;

adultChinese

residents,aged

18+;N=1,115

Cross-sectio

nal

telephonesurvey,

March–A

pril2003

Tolearnview

sandbeliefs

aboutandpsychological

responsesto

SARS

None

CognitiveDim

ension

Emotional

Dim

ension

Yes

Toaidpublic

health

officialsandphysicians

inplanning

fora

possible

expansionof

thecurrentoutbreak

indifferentpartsof

the

world

Personalrisk

Personalrisk

Protectivebehaviors,

e.g.,coveringmouths

whensneezing

orcoughing,hand

washing

with

soap,

face

masks,using

serviceutensilsfor

shared

food

Perceived

likelihoodof

contractingSARSduring

the

currentoutbreak

General

anxiety(State

Trait

Anxiety

Inventory)

Health

serviceuse

Perceived

likelihoodof

survivingSARS,ifinfected

Five-pointscales:“veryunlik

ely”

to“verylik

ely”

Leung

etal.

[49]

aSARS

HongKong–

Singapore

Random

sample

adultresidents

Cross-sectio

nal

telephonesurveys,

May–June2003

Tolearnthepopulatio

ns’

view

sandbeliefs

about

andpsychobehavioral

responsesto

SARS

None

CognitiveDim

ension

Emotional

Dim

ension

Yes

(1)HongKong,

aged

18+;

N=705

Personalrisk

Personalrisk

Protectivebehaviors,

e.g.,coveringmouths

whensneezing

orcoughing,hand

washing

with

soap;

face

masks;using

serviceutensilsfor

shared

food

(2)Singapore,

aged

21+;

N=1,201

Perceived

likelihoodof

contractingSARSduring

the

currentoutbreak

General

anxiety(State

Trait

Anxiety

Inventory)

Perceived

likelihoodof

survivingSARS,ifinfected

Five-pointscales:“veryunlik

ely”

to“verylik

ely”

Health

serviceuse

16 Int. J. Behav. Med. (2009) 16:7–29

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Nickellet

al.

[46]

SARS

Toronto,

Canada

Personnel

from

oneuniversity

hospitalwith

threecampus

sites,39.3%

below

40years;

N=1,983

Cross-sectio

nal

questio

nnaire

survey,

April2003

(1)Todeterm

inetheself-

reported

psychosocial

effectsassociated

with

working

inahospital

environm

entduring

the

peak

ofadisease

outbreak,(2)to

exam

ine

thedeterm

inantsof

these

effects

None

CognitiveDim

ension

Emotional

Dim

ension

No

Universal/Com

munity

risk

Personalrisk

Perceived

deathrate

forSARS

Concern

aboutpersonal

health

Three-point

scale

Networkrisk

Concern

aboutfamily

health

Three-point

scales:“not,”

“slig

htly

tosomew

hat,”

“veryto

extrem

ely”

Peltz

etal.

[81]

Avian

influenza

Israel

Tworandom

samples

Cross-sectio

nal

telephonesurvey,

March

2006

during

anavianinfluenza

outbreak

Tocompare

the

differencesin

public

interest,senseof

know

ledge,

emotions,

andcomplianceduring

theearlyphaseof

anavianinfluenzaoutbreak

inan

affected

area

comparedwith

anatio

nwidepopulatio

nof

thesamecountry

None

CognitiveDim

ension

Emotional

Dim

ension

No

(1)Adults

natio

nwide,

N=

500

Universal/Com

munity

risk

Personalrisk

Perceived

likelihoodof

avianinfluenzaoutbreak

tobecomeawidespreaddiseaseam

onghumanswith

ahigh

human-to-human-transmission

Feelin

gsof

fear,

indifference,stress,and

hope

asaresultof

outbreak

(2)Adults

from

affected

area,

N=103

Five-pointscales

Quahand

Hin-Peng

[82]

SARS

Singapore

Random

sample;

adultpopulatio

n,aged

21+;N=

1,202

Cross-sectio

nal

telephonesurvey,

during

outbreak

2003

Toexam

inepreventiv

epractices,perceptio

nof

self-health

,know

ledge

ofSARS,andappraisal

ofSARScrisis

managem

ent

None

CognitiveDim

ension

Emotional

Dim

ension

Yes

Personalrisk

Personalrisk

Protectivebehaviors,

e.g.,covermouth

whensneezing

orcoughing,hand

washing

with

soap,

face

masks,using

serviceutensilsfor

shared

food

Perceived

susceptib

ility

toSARS:perceivedlik

elihood

ofcontractingSARS

Anxiety

Four-pointscale:

“verylik

ely”

to“veryunlik

ely,”plus

“donotknow

”

Three-point

scale:

“low

”–“m

oderate”–“high”

Ram

baldini

etal.[33]

SARS

Toronto,

Canada

Random

sampling

with

saturatio

n;medical

house

stafffrom

university

hospitalscaring

forSARS

patients;N=17

Qualitativestudy

basedon

grounded

theory,

semistructured

telephoneinterviews

May

andJune

2003

Toexplorethe

perceptio

ns,attitudes,

andexperiencesof

medical

housestaffat

hospitalscaring

for

patientswith

SARS

None

Nostandardized

items;narratives

Emotional

Dim

ension

No

Top

icsRaised

Fearandworry

Concernsaboutindividual

safety,closeothers’safety

SocialAspects

Concern

aboutspreading

diseaseto

lovedones

Socialisolation

RiskAcceptance

Shiao

etal.

[37]

SARS

Taiwan

Nursesin

one

community

hospital,one

secondary,

and

twotertiary

referral

hospitals,aged

20–52;

N=753

Cross-sectio

nal

telephonesurvey,

May

2003,aftera

SARSoutbreak

inApril2003

Todeterm

inethe

perceptio

nsof

risk

ofSARSinfectionin

nurses

andfactors

relatedto

nurses’

considerationof

leaving

theirjobbecauseof

the

SARSoutbreak

None

CognitiveDim

ension

CognitiveDim

ension

Yes

Personalrisk

Personalrisk

Behavioralintentionto

leavejob

Perceived

risk

throughjob:

jobputsmeat

greatrisk

ofexposure

toSARS

Perceived

fatality:

poor

chance

ofsurvival

ifinfected

Networkrisk

Peoplecloseto

meareat

high

risk

ofgetting

SARS

becauseof

myjob

Mychancesof

dyingfrom

SARSarehigher

than

from

cancer

Emotional

Dim

ension

Mychancesof

dyingfrom

SARSarehigher

than

from

trafficaccidents

Personalrisk

SocialAspects

Fearof

falling

illwith

SARS

Peopleavoidmebecauseof

myjob

SocialAspects

Peopleavoidfamily

mem

bers

becauseof

myjob

Close

others

worried

formyhealth

RiskAcceptance

Fam

ilybelievesIhave

ahigh

risk

ofgetting

SARS

Shouldnotbe

lookingafter

SARSpatients

Close

othersworriedthey

mightgetinfectedthroughme

Other

Social–CognitiveCon

structs

Personalcontrolover

infection

Seven-point

scales:“stronglydisagree”to

“strongly

agree,”+“donotknow

”

Int. J. Behav. Med. (2009) 16:7–29 1717

Tab

le1

(con

tinued)

Authors

Disease

Country

Sam

ple

Study

design

Researchquestio

n/study

purpose

Theoretical

model

Coreconceptof

risk

Risk-relatedcognitionsand

emotions

Study

ofrisk

perceptio

n-behavior-

relatio

nship

Tam

etal.

[36]

Avian

influenza

HongKong

Mem

bers

oflocal

nursing

associations,

50%

below

45years;N=999

Cross-sectio

nalmail

questio

nnaire

January–February

2006

Totesttheassumptionthat

professional

experience

with

SARSwould

affect

health

care

workers

attitudeand

preparedness

towards

the

impendingavian

influenzaepidem

ic

None

CognitiveDim

ension

No

Universal/Com

munity

risk

Perceived

likelihoodof

anavianinfluenzaoutbreak

inHongKong

Emotional

Dim

ension

Personalrisk

Fearof

falling

illwith

avianinfluenza

RiskAcceptance

Riskaccepted

aspartof

job

Other

Social–CognitiveCon

structs

Personalcontrolover

infection

Contemplationof

jobchange

Avoidance

attitudetowards

patients

Six-point

scales

Tang

and

Wong[39]

SARS

HongKong

Random

sample,

Chinese

community

residents,aged

60andolder;

N=354

Cross-sectio

nal

telephonesurvey,

March–A

pril2003

Totesttheassumptionthat

perceivedhealth

threats

andefficacy

beliefs

were

thetwocore

dimension

ofmotivationfactorsin

relatio

nto

thepracticeof

SARS-preventive

behaviors

Health

Belief

Model

and

Theoryof

Planned

Behavior

CognitiveDim

ension

Yes

Personalrisk

Protectivebehaviors,

e.g.,washing

hands

with

soap,build

ing

upbody

immunity

with

diet,exercise,

rest,ensuring

good

indoor

ventilatio

n,face

masks

Perceived

vulnerability

with

regard

tocontracting

SARS(three

items):vulnerability

tocontracting

SARS;know

ingor

having

hadcontactwith

infected

persons;having

respiratoryinfectionsymptom

s

Health

serviceuse

Four-pointscales

Tang

and

Wong[38]

bSARS

HongKong

Random

sample;

adultChinese

residents,aged

18+;N=1,329

Cross-sectio

nal

telephonesurvey,

March–A

pril2003

Todeterm

ineratesof

SARS-preventive

behavior

inadult

Chinese

with

different

demographic

background;testefficacy

ofHBM

inpredictin

gthepracticeof

target

preventiv

ebehavior

Health

Belief

Model

CognitiveDim

ension

Yes

Personalrisk

Wearing

face

masks

Perceived

vulnerability

tocontractingSARS(three

items):v

ulnerabilityto

contractingSARS;k

nowingor

having

hadcontactwith

infected

persons;having

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18 Int. J. Behav. Med. (2009) 16:7–29

related and/or which actually were considered integralparts of risk perception by some other studies. While,for example, some authors included fatality ratings intheir core concepts of risk, others presented these asindependent aspects. Similarly, some studies definedemotions, such as fear or worry about SARS, withinthe boundaries of their risk assessment, while others alsoincluded such “emotion items” but placed them beyondthe narrower realm of risk perception by labeling themas separate features.

Classification of risk concepts, as documented in Table 1as well as in the following text, was thus carried out in twodifferent ways. One was noting what the authors themselvesexplicitly referred to as their measures of risk perception, i.e.,what they labeled as or listed among their risk perceptionmeasures. These will be referred to as the “core concepts” ofrisk perception. The other pertained to additional risk-relatedaspects measured in the studies. Table 1, therefore, besideslisting the explicit operational definitions of risk perceptionin one column, contains a separate column listing thoserelated aspects for each study.

Results

Study Characteristics

The major amount of the reviewed studies (75%; N=21)dealt with SARS, only 25% (N=7) focused on the relativelynewer phenomenon of avian influenza. Most of the SARSstudies (90%; N=19) were carried out in 2003, with thelarge majority taking place during the outbreak in East–Southeast Asia–Canada in the first half of that year, whilethe avian influenza studies were conducted at later points,between 2004 and 2006. As might be expected, moststudies were carried out in those parts of the world whichhad been affected most, with Asia clearly in first place.Thirty-two percent (N=9) of the studies originated fromHong Kong, another 36% (N=10) came from eitherSingapore, Taiwan, Japan, Korea, or Laos or comparedsamples from several of these countries. Fourteen percent(N=4) came from Canada and another 18% (N=5) fromWestern Europe and Israel (see Table 1).

Fifty percent (N=14) of the studies were based onsamples from general adult populations, while the other50% dealt with more selective groups. Mostly, these werepersons at particular risk for SARS or avian influenza, suchas health care workers from hospitals where SARS patientshad been treated, travelers returning from mainland Chinato Hong Kong during the SARS outbreak, or poultryworkers. Thirty-nine percent (N=11) of the studies usedrandom sampling, 61% (N=17) purposive methods torecruit their participants.

The large majority of studies (93%; N=26) was based onquantitative survey research designs, using mostly eitherstandardized telephone interviews or paper–pencilapproaches or internet-based surveys in a few cases. Onlytwo studies used a qualitative approach (7%) [32, 33].Almost all studies were cross-sectional (89%; N=25). Only11% (N=3) were based on a longitudinal design or usedcohorts recruited at different points in time.

Concepts of Risk Perception

Not surprisingly, the analysis revealed that the measurementconcepts of risk perception varied widely (see Table 1). Themajority of the studies (71%; N=20) relied on a few singleitems for their core risk measures asking for perceived riskor perceived likelihood of contracting SARS/avian influen-za, for perceived likelihood of a SARS/avian influenzaoutbreak and/or perceived fatality of the disease, partlyadded by ratings of fear or worry with regard to the disease.Some studies, all of which investigated risk perceptions inhealth care workers, named a more diverse range of itemsunder the risk perception label. Besides direct assessmentsof risk and/or fear of getting SARS, these included forinstance perceptions of personal control, worry of closeothers about getting infected, and/or avoidance of patientsdue to infection risk or intention to change jobs [34–36,37]. However, in these studies, too, all measures were usedon a single-item basis. Two publications employed aggre-gate measures of perceived vulnerability (vulnerability,contact with infected persons, having respiratory symp-toms) and/or perceived severity (fearfulness of SARS andworry about one’s own city becoming a quarantine area [38,39]; see Table 1).

A little more than one third of the studies (36%; N=10)explicitly referred to a theoretical model, mostly the HBM(N=6), which also provides a definition of perceived risk(for further details, see the paragraph on the risk perception-protective behaviour relationship below). However, onlyfew studies explicitly laid out their definition of riskperception in the introductory section of their papers [32,40–42].

Further information on the notions of risk perceptioncame from the exploration of the studies’ assessmentmeasures. This analysis yielded a series of categories whichwere then used to classify the concepts. These categories,intended to capture the major communalities and differ-ences between the approaches rather than to represent thenumerous singularities of the different studies, were: (1)psychological processes or dimensions involved in riskperception (cognitive only versus cognitive plus emotion-al), (2) type of judgement (expectancy only versus expec-tancy × value), (3) objects of risk perception (self, network,community/society), (4) type of risk (risk of SARS/avian

Int. J. Behav. Med. (2009) 16:7–29 1919

influenza, risk of other health hazards, social risks), (5) risksituations (general versus situation-specific risks), (6) riskreference points on the health–disease continuum (exposureto a virus, contraction of a virus, falling ill), and (7) riskacceptance3. Below, findings will be presented in line withthese categories.

Processes and Dimensions of Risk Perception: Cognitionsand/or Emotions

The distinction here refers to the different processesinvolved in risk experience and the resulting dimensionsof the concept, i.e., whether risk was assessed in purelycognitive terms, such as asking for assessments oflikelihood to contract SARS or perceived probability ofdying from SARS, and/or whether risk was also measured asan emotional phenomenon, such as experience of fear oranxiety of SARS or avian influenza. A major problem withcategorizing the concepts was due to the fact that aconsiderable number of studies (31%, N=8) relied on thegeneric term “risk” for assessment (e.g., “My job puts me atgreat risk”) mostly without adding any further differentiatedrating. As the authors themselves most often seemed totreat these measures as equivalent to assessments oflikelihood of contracting SARS/avian influenza, they werecounted among the cognitive concepts.

Based on this assumption, 61% (N=16) of the quantita-tive studies chose a one-dimensional approach, the largemajority of which again defined risk perception in cognitiveterms only (N=15). Thirty-nine percent (N=10) included acognitive as well as an emotional dimension in their corerisk concepts, one of which, however, explicitly referencedthe emotional assessment not to the self but askedrespondents to estimate the worry about avian influenzafelt by friends [43]. Terms used for the assessment of risk-related emotions ranged from the relatively mild concernabout contracting SARS/avian flu and worry about con-tracting SARS/avian flu to the more intense fear, which wasused most often, and anxiety (see Table 1). Of the twoqualitative studies, one defined risk perceptions in cognitiveterms but reported also on the emotional ramifications ofthe risk experience [32]; the other focused on the emotionalconnotations of risk in terms of concern, fear, and worry [33].

Despite the overall dominance of the cognitive perspec-tive on risk perception, it needs to be noted that of thosestudies which explicitly tapped risk perception in purelycognitive terms, six (23% of the 26 quantitative studies)actually also assessed emotional aspects. This, however,was done without explicitly labeling these measurements asindicators of risk perception, i.e., these were not parts of thecore risk perception concepts. From this slightly widerperspective, more than half (61%; N=16) of the reviewedstudies took account of cognitive as well as emotionalaspects of risk (be it as an explicit part of risk perception oras a related concept); however, only very few explicitlydealt with the associations between these cognitive andemotional dimensions of risk. Thus, only three of thequantitative studies (11%) gave an account of the em-pirical relationship between measures of cognitive riskassessment and fear/anxiety [44–46], with, for instance,one study reporting a correlation of r=0.64 for theirmeasures of perceived risk and worry about contractingSARS [44]. No study provided an extended discussionabout the ways in which these aspects might relate to andinfluence each other.

Types of Judgements: Expectancy and Value Componentsof Risk Perception

The single most frequently used assessment was perceivedlikelihood or probability of contracting the disease orperceived likelihood of an outbreak or variations of suchmeasures which were included in 58% (N=15) of the coreconcepts represented in the quantitative studies. Eightstudies (31%) relied exclusively on this approach. Nostudy took account of this type of assessment as a “sideaspect,” i.e., explicitly placed it beyond the risk label. Incontrast, another type of probability rating, i.e., fatalityratings or ratings on probability of death/survival wasapparently considered less central. While 46% (N=12) ofthe studies included a measurement of perceived fatality,only 35% (N=9) mentioned this aspect in their coreconstruct of risk, two of which defined risk exclusively asperceived fatality [46, 47]. None of the reviewed studiesconditioned their probability assessments on anticipated oractual behavior change.

Compared to the expectancy component, the value orseverity element of risk seemed distinctly underrepresented,as the overwhelming majority of studies did not requestexplicit ratings of severity from their participants (e.g.,“How severe or serious is SARS?”). If, however, all thestudies measuring fatality as part of their core risk constructwere also counted as assessing severity (35%; N=9), thepicture seemed a little less skewed. Yet, even then, onlyseven, i.e., 27%, of the quantitative studies assessed bothlikelihood of contracting as well as severity/fatality as parts

3 For the report on the number of studies within different categories ofoperationalization, it should be noted (1) that the categories are notalways mutually exclusive, i.e., as many studies contained more thanone measure of risk, the respective studies were also counted in morethan one category, (2) that unless otherwise specified the numbers andpercentages given pertain to the quantitative studies only (N=26),while results of the qualitative studies (N=2) will be reportedseparately.

20 Int. J. Behav. Med. (2009) 16:7–29

of their core risk concept [38, 40, 41, 44, 45, 48, 49]. Whenthose studies which assessed both likelihood as well asseverity/fatality outside of their explicit risk measureswere included [37, 50, 51, 56], the percentage rose to42% (N=11). However, only one study used the multipli-cative term between the two ratings, as specified byexpected utility theory and its health-related applicationssuch as the HBM or PMT [40].

Objects of Risk Perception: The Self, Network,and Community

Another obvious difference in conceptualizing riskperception was related to the risk object chosen, i.e.,who the risk was assessed for. Universal risk, whichcould also be perceived of as societal or community risk,refers to a global perception of outbreak probability orgeneral fatality rates in case of an outbreak in a specificarea. Personal risk perception and network risk percep-tion, on the other hand, are estimations of one’s own andclose others’ very specific probability to contract SARSor avian influenza or to die from this disease as, forinstance, specified in the HBM or PMT. Forty-six percent(N=12) of the 26 quantitative studies focused on thepersonal perspective alone, i.e., assessed the risk for theself without tapping universal risk in their core concepts,while 27% (N=7) measured solely universal or commu-nity sense of risk, and another 27% (N=7) looked at bothaspects. Assessment of network risk was less commonand occurred exclusively in combination with either ofthe other two measures. Five of the quantitative studies(19%) asked respondents to rate risk for close others,either within or beyond their core risk concepts, and bothqualitative studies also reported concerns of respondentsabout the risk/safety of their loved ones.

Type of Risk: Different Health Risks and Social RisksAccompanying Health Risks

Three, i.e., 11%, of the quantitative studies includedmeasures which, besides asking for risk related to SARSor avian influenza, also tapped risk related to otherdiseases or requested direct comparisons between per-ceived risks for different diseases [37, 44, 53].

Another three studies (11%), all of which were lookingat perceived risk in health care workers, also includedsome measure on social aspects of risk, such as perceivinga risk of spreading the disease to others [34, 54] and/or onwhether people believed that their close others felt worriedabout their health due to the respondent’s job in the healthcare sector [34, 37, 54]. This issue of perceived risk totransmit the disease and ensuing role conflicts betweenprofessional and family obligations was also raised by the

qualitative studies (“All residents expressed concern aboutthe potential risk…they posed to their loved ones” [33],p. 382) [32].

The same studies raised another issue which might berelevant in this regard, even if it was not explicitly claimedas part of an anticipated “risk” because it mostly referred toactual past experiences, was that of possible social isolationand stigmatization due to having a job in the health caresector [34, 37, 54]. Again, one of the qualitative studiesalso reported that respondents raised the issue of feltisolation due to their exposure to the virus (“The cancel-lation of rounds and the restrictions placed on socialinteractions with other health care workers created a senseof isolation” [33], p. 383).

Situational Specificity of Risk Appraisal: General Risksand Specific Risks

Variance occurred also in terms of the generality or specificityof risk assessments. Forty-two percent (N=11) of thequantitative studies phrased their questions in uncondition-al/absolute terms (e.g., “likelihood of contracting SARS”),whereas 58% (N=15) asked for qualified/conditional state-ments (e.g., “likelihood of contracting SARS in place x” or“likelihood of contracting SARS when doing y”) orincluded both aspects. In particular, these ratings pertained,for instance, to the probability of contracting SARS indifferent places within a city, such as public places, offices,or public transport [56], when traveling on board of a plane[51], when interacting with recovered patients [41], or riskfrom specific behaviors such as buying live chickens [43].Specified assessments were also requested in most of thestudies which investigated risk perceptions in “professionalrisk groups,” such as poultry workers or - primarily -employees in the health care sector (23%; N=6) [34, 37, 50,54, 55, 57]. Both qualitative studies as well reported on riskperceptions related to a job in the health care professions[32, 33]. Yet another differentiation occurred within thegroup of studies which were conducted outside of acuteoutbreak areas and/or during times without an outbreak.While most studies - just like those conducted in outbreakareas - asked for general risk assessments, an alternative wasto explicitly link the measurement to outbreak occurrence(i.e., likelihood of contracting or dying from the disease, ifone’s own country were hit by an outbreak [47]).

Risk Reference Points on the Personal Health–DiseaseContinuum: Risk of Exposure, Risk of Infection, and Riskof Illness

Differences in the core risk concepts also became evident interms of how perceived risk was specified in relation to thereference points along the personal health–disease contin-

Int. J. Behav. Med. (2009) 16:7–29 2121

uum. The most common choice among the studies which inany form assessed personal risk was to ask for likelihood(or else risk or fear) of infection or for contracting orgetting SARS/avian flu (N=10; 38% of all quantitativestudies). A few studies (N=4; 15%), however, in slightlydifferent terms asked for ratings of risk of exposure toSARS/avian flu [34, 37, 54, 55], and instead or in additionrequested respondents to indicate their fear or likelihood offalling ill or fear of getting sick (N=7; 27%) [34–36, 37,43, 54, 55].

Risk Acceptance

Finally, five (19%) of the quantitative studies introducedyet another feature (four of them explicitly as part of therisk construct), asking health care workers whether theyaccepted risk as part and parcel of the job [34–37, 54].Rambaldini et al. [33] in their qualitative study on healthprofessionals’ reactions to the SARS outbreak also reportedon this aspect of risk perception.

The Risk Perception–Protective Behavior Relationship

More than half, i.e., 57% (N=16) of the 28 reviewedstudies investigated the role of risk perception for behaviorsor behavioral intentions aimed at avoiding infection.Mostly, these were individual hygiene or lifestyle behaviorsor behaviors related to handling live chickens (N=11;39%). A few studies (N=3; 11%) dealt with socialavoidance behaviors/intentions, such as health care workersintentions to leave their job [37, 57] or tendencies in thegeneral public to avoid recovered SARS patients [41]. Onestudy investigated behavioral intentions for influenzavaccination as a result of SARS risk perception [53] andanother compliance with quarantine [32].

The remainder of the studies (43%; N=12) was eitherof a purely descriptive–epidemiological nature or had theirfocus on potential determinants of risk perception. Ofthese, only two (17%) explicitly based their risk conceptson a theoretical model, i.e., the PMT [40] and Weinstein’s[58] Optimistic Bias concept [42]. This low percentage ofmodel-based research increased to 50% (N=8) in thesubgroup of studies which investigated the potential roleof risk perceptions as determinants of health-relatedbehaviors or behavioral intentions (N=16). Of the sevenquantitative studies which were model-based, three usedthe HBM [41, 48, 51]; two further studies [38, 39] namedthe HBM as well as the Theory of Reasoned Action/Theory of Planned Behavior [28, 29] and Bandura’s SelfEfficacy Theory [59] as the basis of their work. Anotherchoice presented by one of the studies [44] was thePrecaution Adoption Model [60], and one further study[53] based its research on a state-dependent expected

utility framework [61, 62]. In addition, the HBM and PMTwere claimed by one of the qualitative studies, whichexplored the association between risk perception andcompliance with quarantine [32]. In three of the quantita-tive studies all or most of the variables introduced by therespective model were tested within a multivariate analysis[39, 48, 51], while the other studies used major compo-nents of the theories and/or tested bivariate relationshipsbetween separate model components and protectivebehaviors. Only one of the model-based studies had alongitudinal design [63].

Discussion

In the following section, the theoretical concepts of riskwhich emerged from the reviewed articles as well as therole risk perceptions play for protective behaviors will besummarized and examined. Strengths and deficits of currentempirical risk perception research in terms of theirtheoretical foundations will be pointed out and conclusionswill be drawn regarding implications for future research andalso for practical purposes such as the development anddesign of public health risk messages.

Concepts of Risk

The majority of the reviewed studies were launched as arapid response to the SARS outbreak in 2003 or as animmediate reaction to the first human cases of avianinfluenza in some Asian countries. The purpose was thussocioepidemiological in most cases, aimed at assessingpsychological reactions towards the SARS or avianinfluenza threat in general populations or in specificsubgroups, such as health care workers, to predict adoptionof protective behaviors and thereby to provide data forfuture intervention planning. This predominantly practice-oriented intent might explain the pervasive lack ofconceptual elaboration on the perceived risk concept thatwas encountered. In fact, only few studies explicitlydefined or theoretically explained their notion of perceivedrisk. Instead, it was mainly the operational level, i.e., themeasurement instruments, which provided indicationsabout the underlying notions of risk perception.

The concepts emerging this way turned out to be quiteheterogeneous - and this finding related to a whole numberof features characterizing the risk concept, including: thepsychological processes or dimensions involved in riskperception (cognitive only versus cognitive plus emotion-al), type of cognitive judgement (expectancy only versusexpectancy × value), objects of risk perception (self,network, community/society), type of risk (SARS/avianinfluenza risk, other health risks, social risks), risk

22 Int. J. Behav. Med. (2009) 16:7–29

situations (general versus situation-specific risks), riskreference points on the health–disease continuum (exposureto a virus, contraction of a virus, falling ill), and riskacceptance. The variance which occurred on all thesedimensions clearly indicated that behind the common claimto investigate “risk perception” there was only very limitedagreement on what exactly constitutes such perception ofrisk and how it should be measured. This, however,suggests that the empirical findings from the differentstudies on risk perception might be extremely difficult tocompare and evaluate within a common context.

One of these differences, which actually touched the verycore of the construct, became evident with regard to thechoice of defining risk perception as an exclusively cognitiveor as a cognitive–emotional phenomenon. While it seemsplausible that a pandemic influenza outbreak constitutes ahighly uncertain, ambiguous, and threatening situation,where lay people tend to fall back on immediate, visceral,and emotionally loaded concepts and images rather thanrational probability assessments, this notion needs empiricaltesting: at different points in time, before and during anoutbreak, and with different subgroups within generalpopulations. However, only a little more than half of thereviewed studies looked not only at cognitive risk assess-ment but also at SARS- or avian-influenza-related emo-tions. Only about one third of the quantitative studiesexplicitly perceived of this emotion-based judgement as adimension of risk perception and not as some externalaspect. And whatever the concept - “risk as feelings” or“risk and feelings” [19, 64] - neither of the studies providedfurther theoretical elaboration on why fear or worry wereperceived of as part of risk perception or seen as separatefeatures, just as there was little interest in the empiricalrelations between cognitive and emotional aspects of riskperception. At this point, empirical research on SARS andavian influenza risk perception can thus provide fewinsights into the issue of whether emotions result fromcognitive risk assessment and/or precede such cognitions orhow cognitive and emotional processes interact in creatingnotions about “risk” and influence behavior. While themostly social–epidemiologically oriented studies whichformed the basis for the current review were not designedand intended to investigate such issues, future researchshould be directed towards this area as findings would notonly be relevant for theory development but also for theways in which health risk messages will have to beframed and designed in case of future outbreaks.

Another notable issue was the considerable heterogene-ity in the operational terms chosen to measure risk affect,which ranged from the relatively mild concern and worry tofear or anxiety. Affirmative responses will probably bestronger for worry or concern than for anxiety, which makesthese findings difficult to compare and evaluate. Also,

while worry and concern can be perceived of as cognitiveaspects of emotion [65, 66], anxiety and particularlyfear, might tap more strongly into an affective-visceraldimension. These aspects are likely to relate differentlyand interact differently with cognitive probability ratingsof disease [66], but that notion, too, requires empiricaltesting.

Another difference concerning the essence of the riskparadigm became apparent in the way in which the studiesmeasured the type of risk judgements, i.e., whether theyassessed risk in terms of the expectancy and/or the valuecomponent. What came as a particular surprise was that onlyfew studies actually relied on the theoretically established“probability × severity function” which posits that people’schoices are a product of assessments of probability andutility/desirability of options [2, 5–8]. First, quite a numberof studies did not use a differentiated concept of risk at allbut simply asked respondents to rate their risk to contractSARS. While this type of assessment, particularly whenrelated to terms like “contracting” or “getting” a disease, canbe considered predominantly cognitive and conceptuallyclose to the “likelihood of contracting–measure,” there isalso plausibility in the assumption that the term riskinherently entails severity aspects and/or is likely to incurmore negative emotional connotations than the more neutrallikelihood and is therefore conceptually closer to “fear.”This is also supported by psychometric paradigm-relatedresearch, suggesting that lay people tend to judge eventswith low probability but high catastrophic potential such asnuclear accidents as “high (dread) risk” [3, 4].

Furthermore, while probability of infection or of contract-ing disease was clearly the most common notion of riskperception, the value - or severity - component met withconsiderably less interest. However, a substantial number ofstudies included measures of fatality and it might be arguedthat fatality ratings are in fact assessments of value (i.e.,severity) rather than measures of expectancy. Indeed, inmany studies which used fatality measures, these wereexplicitly introduced as measures of severity of disease.Such a claim certainly has some degree of content validity,since most people would consider diseases they believe tobe potentially fatal also as serious, even if from a purelystructural–systematic perspective, probability of death rat-ings clearly refer to an expectancy-, not to a value-element.However, even when these ratings were counted asmeasuring severity, it seemed that severity was not generallyconsidered to be an integral part of the risk concept, but wasmore often presented as a separate entity. This was alsoemphasized by the fact that only one study actually used themultiplicative term specified by the HBM and PMT [40],i.e., the product of probability and severity. All thesedeviations from standard definitions of risk occurred mostlywithout any explanation of the rationale behind them —

Int. J. Behav. Med. (2009) 16:7–29 2323

even in cases where models such as the HBM or PMT hadbeen referred to in the theory sections of the papers. Testingthe effects of subcomponents and their possible interactions,however, might yield essential information for effective riskcommunication, for instance, in terms of being able tospecifically target unrealistically low perceptions of occur-rence likelihood versus underestimations of severity.

Further variance was encountered in terms of the objectsrisk was rated for - a problem that Brewer et al. [26, 27]have pointed out and which also became apparent in thepresent review. The most common assessment related to theself (personal risk), but some studies also measured riskperceptions for close others (network risk) and/or for thesociety/community as a whole (universal or societal/community risk). While network risk was commonlymeasured in addition to personal risk, societal/communityrisk was most often assessed instead of personal risk. Whilefor respiratory infections risk of self and risk of others - dueto “social contagiousness” - are bound to be correlated, theyare also liable to differ. Judgements on personal likelihood tocontract infectious disease are subject to considerations ofindividual immune competence and host resistance. Sincediseases such as SARS and avian influenza are stillrelatively new and unknown in the wider population, peopleare likely to refer to personal experiences with diseaseswhich might seem to bear some resemblance to “normal”flu or other infectious diseases. Based on differing individualexperiences with susceptibility or immune competence, therecould be considerable divergence between personal ratingsand those for the population in general. In addition,tendencies towards an optimistic bias [58] should influencepersonal ratings to be generally lower than those for theoverall population. Harris and Middleton [67], who inves-tigated risk perceptions for various health hazards instudents, showed a gradient for most of the rated conditionsdepending on who the rating was made for: from lowestratings for the self to slightly higher ones for very closeothers, even higher ones for acquaintances, to highest scoresfor unknown others. Even if such tendencies should be lesspronounced for respiratory infections such as SARS,which - compared to lifestyle disorders - tend to be “equal-opportunity diseases,” subjective concepts about individualsusceptibility or resistance capacity might produce quitedifferent results depending on who the risk is assessed for. Inany case, if the goal is to determine how risk perceptioninfluences protective behaviors, personal risk assessmentshould be the first choice, while the other perspectives -while also important - should provide additional rather thansurrogate insights.

Surprisingly few studies extended their view from thehealth dimension of SARS or avian influenza risk to othertypes of risks. Thus, only three studies asked theirrespondents to also rate other disease risks or to make

direct comparisons between risk of SARS and other risks[37, 44, 53]. Such comparisons could provide importantinsights, as the motivational potential of risk perceptions incase of an outbreak depends not only on their absolute butalso their relative strength when compared to other healthconcerns. Relative importance of pandemic influenza risk,however, also relates to other types of risk which might beinvolved in a pandemic influenza hazard such as, forinstance, social risks. Especially studies looking at healthcare workers did assess not only personal health risks butalso the perceived risk of spreading the disease to familyand friends and/or issues of stigmatization and socialisolation [32–34, 37, 54, 55]. While in the reviewed studiesstigmatization and social isolation were mostly assessed interms of actual experience, it is plausible to assume thatanticipations of such processes (“social risk cognitions”)are relevant for shaping the sum of pandemic influenza riskconnotations and thereby influences behavioral responses.Above and beyond risk to one’s personal health, antici-pations of being responsible for spreading the virus to lovedones or being socially excluded because of one’s job mightdetract considerably from readiness to accept risk and mightinterfere with professional behavior in health care workers.This issue was also explicitly reflected in the concept ofrisk acceptance, which was brought up by a few studies[33–36, 37, 54, 55]. How professional groups who have akey role within containment plans balance personal andsocial risk expectations with their professional roles, howthey weigh the risk of getting infected and in turn infectingothers against the risk of jeopardizing their professionalidentity, is a concern which needs to be faced and dealt within the course of effective intervention planning. Otherwise,a sudden lack of readiness of professionals will disrupt carefor those who have already become patients or get in theway of public health containment measures and endangercollective protective action.

Social considerations are, of course, not restricted toprofessionals, as Yiang et al. in a contribution to the currentissue, have shown. They investigated determinants of riskperception within Chinese communities in the Netherlandsand the UK, pointing out the role of social costs of infectiondue to anticipated stigmatization processes. Similarly, arecent qualitative study on Hong Kong SARS survivors[68] showed that stigmatization and discrimination was apervasive and traumatic experience, a finding which led theauthor to conclude that anticipations of such socialexclusion processes might well endanger the effectivenessof public health measures should there be another majoroutbreak (see also [69]). Particularly in the early stages ofan outbreak, when people are perhaps anyway more readyto interpret ambiguous respiratory symptoms as indicationsof “normal” flu than of a life-threatening disease, theymight thus deliberate and delay, hoping that the symptoms

24 Int. J. Behav. Med. (2009) 16:7–29

will turn out harmless and go away, rather than take the riskof being prematurely identified as a carrier of a potentiallylethal virus. Social risk perceptions such as these couldeasily cancel out motivating effects of perceived diseaserisk. Thus, the so far most commonly used one-dimensionalnotion of SARS/avian influenza risk as a “mere” healthhazard might fall short of grasping the whole of whatmakes up lay persons’ or health professionals’ ideas aboutpandemic influenza risk.

Another angle which remains to be investigated by futurestudies is the relative relevance of health risk perceptionscompared to perceptions of other types of life risks. In one ofthe original contributions to the current issue, Voeten et al.reported lower avian influenza risk perceptions in a sampleof Chinese residents in the UK and the Netherlands incomparison to the general populations in these countries.According to the authors, an explanation for this rathersurprising finding might be found in studies such as the oneby Lai and Tao [70] who showed that Chinese people ingeneral seem to be far less concerned about disease risksthan about risks that threaten, for instance, national stabilityand economic development. In the same vein, two of thereviewed studies [40, 42] reported lower risk perceptions inAsian as compared to European or North American samples.While this variation may largely be due to social–culturaldifferences, socioeconomical considerations may also play apart. Thus, people living under economically precariousconditions may place a relatively lower value on healthconsequences, at least as long as these remain speculativeand distant when compared to other more immediateeconomic daily hazards. This might be specifically relevantfor groups such as poultry workers who in case of an avianinfluenza outbreak will find themselves between a rock and ahard place when evaluating health vs. economic risk. Viceversa, as an example from the other end of the socioeco-nomic spectrum, globally mobile executives might at somepoint have to face the “bads” of globalized risk society as thealmost inevitable flip side of the “goods” [71, 72], having toweigh the risk of health damage against that of economiclosses due to restricting travel. Future research will haveto take up the challenge to understand the processes bywhich pandemic influenza risk is grounded in the (sub)cultures and social structures of different countries and theirrespective worldviews [4] in order to effectively tailorcommunication strategies to specific groups, particularlythose who might face a heightened risk of exposure toinfluenza viruses while at the same time facing economic orsocial risks, like for example poultry farmers and vendorsin the case of H5N1.

As for the generality or specificity of risk situations, alittle less than half of the studies asked for general riskassessments, i.e., overall probability to contract SARS orgeneral fatality rates, while a bit more than half qualified

their assessments in one way or another. What wasrequested were, for instance, risk ratings for specificregions or ratings for situational circumstances, such asprobability of infection when traveling or due to working ina specific job such as in the health care sector. Particularly,behavior-specific risk ratings should be expected to relatemore closely to particular protective behaviors than generalrisk perception. In an outbreak situation specific assess-ments can help identify “critical areas of risk perception”where people perceive unrealistically low or high risk andwhich might warrant intervention. Vice versa, general riskexpectations provide an interpretational background forbehavior-specific risk perceptions because, even whenspecific risks are perceived of as not particularly high, thisdoes not necessarily imply that risk perception in general isalso low and vice versa. Therefore, both types of risk per-ception are essential and should not be treated as surrogates.

Yet another type of qualifying assessments becameapparent in the small group of studies which were conductedoutside of acute outbreak areas. It should make a differencewhether respondents are asked for general statements (“prob-ability of contracting SARS/avian influenza”) or whethersuch ratings are conditioned on the case of an outbreak(“probability of contracting SARS/avian influenza if anoutbreak occurred in the country/region”). The latter shouldyield higher risk perceptions than those without qualification,as in the former case the disease has yet to arrive and mightseem not only geographically but also psychologically moreremoved. In general, hypothetical risk perceptions such asthese are hard to compare to “real” risk perceptions underoutbreak conditions and do not refer to exactly the samephenomenon. Unlike chronic diseases, which develop grad-ually, pandemic influenza tends to be a more binary or “on–off phenomenon”, which sets quite distinct frames for riskperception under conditions of outbreak versus no outbreak.It would be profitable to study how hypothetical riskperceptions in a non-outbreak situation develop underconditions of imminent threat and whether perceptions ofhypothetical risk can be extrapolated to actual risk percep-tion. This, of course, would require introduction of long-termcontinuous surveillance studies.

Finally, variance also occurred with regard to thereference point chosen for assessment on the health–illnesscontinuum. While most studies measured “likelihood ofcontracting SARS/avian influenza,” there were also somewhich asked for ratings of “exposure to SARS” or “fallingill with SARS/avian influenza.” Such diverse semanticscould evoke different connotations. Exposure occurs priorto actual contraction or acquisition. Health care workers inan outbreak area might perceive a considerably higherlikelihood of exposure to pandemic influenza than ofactually contracting the disease because they might hopethat immune competence and control measures would

Int. J. Behav. Med. (2009) 16:7–29 2525

protect them from actually being infected. And while as arule contracting the virus will also mean falling ill with thedisease, the latter expression seems to indicate a stepforward on the semantic continuum and to evoke strongeremotional connotations than a more neutral rating onprobability to contract pandemic influenza.

The Risk Perception–Protective Behavior Relationship

As outlined in the introductory section of the paper, muchof the research work on the health risk perception–protective behavior relationship has been characterized byconceptual as well as methodological problems, leading tosubstantial interpretational ambiguity. The specific set ofpapers on SARS and avian influenza risk perceptionreviewed here seems to make no exception in this regard.Just as there was little theoretical elaboration on the riskconcept itself, only a minority of the subgroup of studieswhich investigated the possible predictive role of riskperception for protective behaviors could actually beconsidered model-based. The current review showed that,of the 16 studies which were dealing with this issue, onlyhalf referred to any theoretical concept or model, most oftenthe HBM. Of these, again only less than half actually testedthe full respective model.

The resulting lack of opportunity for studying thecomplexity of the decision-making process is bound to alsoaffect the extent to which findings for the relationship betweenrisk perception and protective behaviors can be interpreted. Toobtain a comprehensive picture of how decisions aboutprotective behaviors are made, risk perceptions need to betested in comparison to and/or in concert with othercognitions, such as those specified by the HBM or PMT, i.e., perceived efficacy of countermeasures (outcome expectan-cies) or the costs and benefits associated with behavioralchange. For instance, the social aspects of pandemic influenzarisk discussed above could also be conceptualized in terms ofcosts associated with risk-related behavior, as specified by theHBM. Thus, as outlined above, the cost factor “anticipatedstigmatization” (or “social risk perceptions”) might neutralizemobilizing effects of health-related risk perceptions, forinstance by precluding disclosure of symptoms. Also, toanswer the question “how high is high enough”with regard torisk perception and “how high is too high” becausehelplessness sets in, risk cognitions would have to be jointlyinvestigated with their emotional connotations and alsotogether with outcome expectancies about control measuresas well as self-efficacy expectancies. Taking action is bound todepend not only on motivating factors such as risk perceptionbut also on enabling features like perceived availability ofeffective behavioral options or perceived social norms. Also,the construct of risk acceptance introduced by a few studiesmight further contribute to successfully predicting protective

behaviors. Even high health risk perceptions in terms oflikelihood to contract an infection might fail to havemobilizing effects if the related social risks are given greaterweight, so that the health risk, even if high, is tolerated.Thus, a more systematic application of multifactor modelswould allow for far more complex insights into the workingsof risk perceptions in shaping behavior than the most oftenused tests of bivariate relationships alone.

In addition, the utility of the data presented by thereviewed studies might be constrained by design deficits ofthe studies and ensuing validity problems. Despite theirclaim to investigate the motivating effects of risk perceptionon health-protective behaviors (behavior motivation mod-el), the overwhelming majority of the studies which lookedat risk perception–protective behavior relationships actuallyinvestigated risk perception–behavior accuracy models[26]. That is, due to the dominating correlational studydesigns, positive relations between risk perception andbehaviors, like hand washing, wearing of face masks, orbeing careful in handling live chickens, indicate little morethan the fit between perceptions of own protective behaviorand risk (accuracy hypothesis), as people who protectthemselves are also more likely to perceive less personalrisk because of these protective behaviors. This ambiguitywas exacerbated by the fact that no study attempted tocompare behavior-conditioned and behavior-unconditionedrisk perceptions, i.e., looked at risk perceptions with orwithout anticipated or past behavior change, as suggestedby Brewer et al. [26, 27]. Not taking this precaution canlead to dilution of risk perception effects, as somerespondents might already factor in behaviour change whenestimating their personal risk.

On the other hand, one could argue that pandemicinfluenza constitutes a special case. The investigation ofthis type of hazard might make studies less susceptible tointernal validity threats than either studies on chronicdisease or on types of acute disease which can be offsetby vaccination, as in the Lyme disease example used byBrewer et al. [26]. Unlike the individual long-termdevelopment of chronic disease (e.g., coronary heartdisease), where there is an extended time-frame forbehavior-change, an outbreak situation creates a massive,collective, and acute threat, i.e., it has “dread potential” interms of the psychometric paradigm, and people tend to feelmore out of control [3, 4]. It seems likely that in the firststage of an outbreak risk perception is strongly influencedby the nature of the hazard and the way it is communicatedby media coverage of case and fatality incidents. Thatimpact might be more overwhelming than any effect whichcountermeasures might have on risk perception. In fact, thefew longitudinal or cohort studies in this review found thatduring the initial phases of the SARS outbreak in 2003there was a steady increase in risk perception, which only

26 Int. J. Behav. Med. (2009) 16:7–29

leveled off in later phases [45, 56]. Moreover, unlike othertypes of infectious diseases, which can be neutralized byalmost 100% effective vaccinations, in case of pandemicinfluenza people cannot be certain about the effectivenessof preliminary vaccines or behavioral containment mea-sures, so that it is unlikely that even strict adherenceto protective behaviors will nullify any notion of risk.However, while these characteristics of pandemic influenzarisk might lessen interpretational ambiguities, it will noteliminate them, particularly when studies are conducted inthe latter phases of an outbreak. As consistent behaviorchange is more likely to have occurred by then, it is alsomore likely that behavior motivation effects are wiped outor reduced by appraisal effects (lower risk perceptions dueto higher protective behaviors). Studying the change ofpandemic influenza risk perceptions and their “true”influence on protective behaviors over time thereforeremains an important objective, requiring not only studieswith longitudinal designs, starting after potential futureoutbreaks, but also long-term surveillance studies which areinitiated before an actual outbreak occurs.

Limitations

It certainly needs mentioning that the classification ofstudies into the different categories can be disputed in someregards, due to the problems outlined in the “Method”section. Thus, for instance, to categorize the studies whichdirectly asked for ratings of “risk” (e.g., “My job puts me atgreat risk”) into the category of cognitive risk judgements,analogous to the measurements of likelihood or probabilityof infection, can be considered problematic, as the term“risk” is affectively less neutral than “likelihood” or“probability”. Also, in general, the descriptions of mea-surement instruments in the reviewed articles were notalways sufficiently precise to permit completely clear-cutcategorization. Similarly, it cannot be ruled out that to someextent the differentiation into “core concepts of riskperception” and “side aspects” or “risk-related aspects”suffered from misclassification. This might, for instance,have happened in cases where authors explicitly labeled theirratings on probability of infection as their measures of riskperception but then also measured severity aspects withoutfurther comment on whether this was conceived of as a part ofrisk perception or not. As most studies provided no theoreticaldefinition or elaboration on how risk perception wasconceptualized, it cannot be ruled out that in some cases theapparent distinction in measurement was not a deliberateattempt at conceptual differentiation. Likewise, in someinstances where studies were published in rather brief formats,it cannot be excluded that the empirical work actually wastheory-based, but, due to extremely short background sectionsin some articles, this might not have been discernible.

Conclusions

In a recent study, Wu et al. [73] put forward anepidemiological model which tested pathways to reducethe impact of pandemic influenza by household interven-tions. The authors reported that already moderate levels ofbehavioral compliance would bring about substantialpopulation-level benefits and also that individual decisionswhich would influence compliance might differ widely. Theauthors concluded that there is a clear need for psychobe-havioral surveillance studies to estimate levels of compli-ance and to identify factors which would influence thedecisions of individuals and households.

The presently reviewed body of studies providespreliminary evidence with regard to one such factor, i.e.,risk perception, and is valuable insofar as the studies offerfirst insights into peoples’ reaction to new or reemerginghealth threats such as SARS or avian influenza. However,in order to gather more systematic and compelling data,which can be compared and evaluated within the context ofothers studies, and in order to build a sound evidence base,future studies in the field positively need to carry out moretheoretical groundwork which can guide the developmentand choice of risk perception concepts and measurementsas well as study designs. It was one of the most surprisingfindings of this review that the risk perception label wasoften used with little explicit explanation of what it stoodfor, as if risk perception were a self-evident and homoge-neous concept. However, closer scrutiny of the studiesrevealed that this common label actually covered quite dif-ferent notions — a, which would make it extremelydifficult to draw any generalized conclusions from theresulting body of data. In view of this finding, it might beworth striving for a working consensus on indispensablecore measures of risk perception, particularly for futuresurveillance and monitoring studies. As stated above, manyof the studies were initiated in an ad hoc fashion as an acuteresponse to outbreaks of SARS and human H5N1 cases andnot as an explicit attempt at testing theory. However, the callfor model-based risk perception research [15, 74] does notexclusively aim at benefiting theoretical knowledge aboutwhat “is” and what determines risk perception. A thoroughunderstanding of how perceptions of risk develop and inwhat way and by which mechanisms they influencebehavior is an indispensable prerequisite for the develop-ment of effective health risk messages and for promotingprotective behaviors in case of an outbreak. To define thepurpose of a study as predominantly pragmatic in terms ofwanting to provide data for planning does not implynonnecessity for theoretical groundwork. Otherwise, thedata gathered might be difficult to interpret and of limitedvalue, not at least for the practical purpose they wereintended for in the first place.

Int. J. Behav. Med. (2009) 16:7–29 2727

“The threat of an influenza pandemic is, at present, one ofthe most significant public health issues our nation and worldfaces” - so a statement of the US Commissioner of Food andDrugs, Andrew von Eschenbach in a press release from April2007 [75]. While some medical advances have been made,thus for instance a preliminary vaccine has been developedto counteract human-to-human transmission of H5N1, thereis still agreement that an initial outbreak cannot be controlledby medical strategies alone. Apart from the fact that thevaccine offers only limited protection, concerns have alsobeen voiced that the medication which has predominantlybeen stockpiled so far, i.e., Tamiflu (oseltamivir), might bemeeting with increasing resistance [76–78]. Also, it is by nomeans certain that the next epidemic actually will be a H5N1outbreak, or if another new virus will emerge on the scene.Thus, traditional public health containment strategies willstill be a centerpiece of preparedness planning. To provide amore profound basis for this type of planning and to enableeffective health communication, research on pandemicinfluenza risk perception will have to progress from itscurrent preliminary ad hoc stage into a more systematic,methodological, and theory-based endeavor.

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