Pandemic (H1N1) 2009: The Public Health Response

Dr. Sylvie Briand

Global Influenza ProgrammeWHO, Geneva

Faces of the Pandemic: Old and New

Pandemic (H1N1) 2009 Overview

• As if 15 August 2010, 215 countries and territories have reported cases

• 18,631 laboratory-confirmed deaths in 125 countries

• Official numbers significantly underestimate actual numbers

• Widespread community transmission in all areas

• From April 2009 to August 2010

Pandemic Response Tools

1918 1957 1968 1997 2003 2009

Spanish flupandemic

Asian flupandemic

Hong Kong flupandemic

A (H1N1) 2009pandemic

H5N1 Asia504 C299 D

H5N1 Hong Kong

18 Cases (C) 6 Deaths (D)

Sulfonamides(1939)

Penicillin(1945)

Cephalosporins (1964)

Aminoglycosides (1943)

Erythromycin(1952)

Introduction of other classes of antibiotics

Antibiotics

Amatadanefor influenza (1966)

Rimatadane(1993)

Neuraminidase inhibitorOseltamivir and Zanamivir (1999)

Antivirals

PH measures (i.e. school closures, mask , mass gathering) Non-pharmaceuticalInterventions

Inactivated Influenza Vaccine (IIV) (1944) Improved IIV (1960 purified)

IIV(1968 fragmented)

IIV(1980 sub-unit)

GISN (1952)

Cell-based IIV

(2007)

LAIV (live-attenuated, 1960, Russia) Adjuvanted

IIV(1997)

VaccinesLAIV

(2003, USA)

Pandemic Response ToolsVirus and benefit sharing discussion (2007) PIP OEWG

Pandemic PreparednessGuidelines (1999): 3 phases

PP guide(2005): 6 phases

PP guide (2009): 6 phases

Revision of International Health Regulations (IHR) (1969)• Plague • Yellow fever • Cholera

IHR revisionIncludes all Public Health Emergencies ofInternational Concern

(PHEIC) (2005)

1918 1957 1968 1997 2003 2009

Spanish flupandemic

Asian flupandemic

Hong Kong flupandemic

A(H1N1) 2009pandemic

H5N1 Asia504 C299 D

H5N1 Hong Kong

18 C 6 D

SARSGlobal

>8000 C 774 D

Assessment of Severity Characteristics

Source: Weekly Epidemiological Record, 13 November 2009.

Infection and Disease• Broad clinical spectrum of

disease– High proportion of pauci or

asymptomatic– 10-50% of GI symptoms– Severe viral pneumonia in

healthy adults– 10-20% of hospitalizations

required ICU• Groups at increased risk of

severe disease once infected (hospitalization, ICU, death)

– Chronic medical conditions– Pregnant women– Very young and the elderly– Obese – Aboriginal/ethnic minorities– 40% were previously healthy

Highest rates of clinical infection:

Teens and young adults

Highest rates of hospitalization:Children < 5 (median age 20s-30s)

Highest rates of death:Adults 50-64 (median 35-51; younger age group compared to seasonal influenza)

How is this pandemic different?– First large scale response under the revised

International Health Regulations (2005) framework– Global sharing of information and viruses through

expert networks • E.g. Virus sharing: As of 5 May 2010, 155 countries shared 26,066

specimens with WHO Collaborating Centres– Significant, previous pandemic preparedness efforts,

incl. the area of risk communication• E.g. 140 countries with pandemic preparedness plans before the

pandemic – Access to

– antibiotics – antiviral– vaccines (developed and available in 6 months)– high-quality health care (i.e. ICU)

– Early detection and response at international level• E.g. Virus sequence made publicly available on 25 April 2009• RT-PCR kits available on 2 May 2009

Spread of Pandemics

• 1957: Spread throughout China in 6 weeks and throughout the world in 6 months

• 2009-2010: Started in North America; spread to all continents in less than 9 weeks and throughout the world in 10 months– Announcement of pandemic phase 6 on 11

June 2009• 74 countries reporting cases of (H1N1) 2009 virus

– West Africa reported A (H1N1) pandemic outbreaks only in early 2010

Continued Global Spread of H1N1 April 2009 - February 2010

April 2009 May 2009 (1 month) July 2009 (3 months)

September 2009 (5 months) December 2009 (8 months) February 2010 (10 months)

Proposed 2009 Phases Structureand Pandemic Disease "Risk"

1 - 3

Sustainedhuman-to-human

transmission

Time

Predominantly animalinfections;

Limited transmissibilityamong people

Geographic spread

Post Peak

Post Pandemic

5 - 6

4

Rapid

containment

Early Responses to the Pandemic

• No travel restrictions.• Attempt to contain the spread with societal

measures (e.g. school closures or antiviral prophylaxis in close communities).

• More information is needed to assess the impact and cost effectiveness of the various strategies.

Molecular Evolutionary Analysis of the Influenza A (H1N1) pdm, May–September, 2009: Temporal andSpatial Spreading Profile of the Viruses in Japan. (Shiino T et al. PLoS ONE 1 June 2010, Vol. 5:6)

School closure: 16 May – 5 June (Kobe prefecture)

Source: Infectious Agents Surveillance Report, 2009

Time course of the H1N1 pandemic for select countries*

Peak(s) (N.B. Not all countries have detected a "peak" in activity )Peak(s)** Peak(s) (N.B. Not all countries have detected a "peak" in activity )

Sporadic Cases Detected

Cases detected

Data sources vary by country and include: country-provided epi curves of case onset; ILI consultation rates; Virus isolates by date; percentage of positive specimens collected; media source (first case report for some countries).

*Table developed by: Maria Van Kerkove PhD, MRC Centre for Outbreak Analysis and Modeling, Imperial College London ** N.B. Not all countries have detected peak inactivity.

Global Spread of Pandemic (H1N1) 2009, Co-circulation of Viruses

Challenges

Surveillance and Severity Assessment

• Severity assessed and monitored with a basket of indicators– 3 dimensions:

• Severity of the disease (clinical epidemiological and virological)• Vulnerability of the population• Capacity to respond

• During the pandemic, the heterogeneity of systems and indicators has been a major challenge for global monitoring

• Different age groups• No standardized definition of underlying factors• No standardized definition of Influenza deaths• Different laboratory capacity

• More than 100 countries have very limited or no influenza surveillance capacity

Phases in Preparedness Guidelines

• Since 1999, pandemic phases have been used as a tool for planning pandemic responses at global and country levels.

• Pandemic phases were never used during a pandemic. • Main challenge: Publication of new guidelines in early 2009

presented a communications challenge, namely helping the media and Member States (MS) understand the meaning of the phases.

2009 version

Communications• The first phase went well: Early announcement,

transparent communication• Then things started to unravel: Conspiracy theories

started to spread in media and through networks on the internet

• The consequences were :– Misunderstanding of the public health response from the

general public and low uptake of vaccine in some countries– A number of parliamentary enquiries and external reviews of

technical agencies' responses to the pandemic• New sources of information dissemination have to be taken

into account in future pandemic preparedness plans: internet, blogs, virtual social networks

Naming of the Pandemic

Global Health Challenges

• International mass gatherings (Hajj, FIFA World Cup, Vancouver Olympics)

• Global solidarity – Access to antivirals

• Deployment to 72 countries – Access to pandemic vaccines

• Deployment started in November 2009

• As of 30 August 2010, reached 72 countries

• 73 million doses

Concluding Observations• Certain events were correctly anticipated

– Eventual emergence of a pandemic– Spread was more rapid than in the past

• Certain events theoretically acknowledged, but still a surprise – Started in North America– Origin of pandemic virus came from swine H1 viruses

• Certain events were simply surprising– Effectiveness of one vaccine dose

• Preparedness was crucial but remains incomplete• Impact of control measures on the spread and

severity of the disease are being assessed

Acknowledgments

• Hundreds of people have contributed to the global response to the pandemic (H1N1) 2009– Global Influenza Programme and WHO regional

offices – Technical partners, including national CDC, ECDC,

national influenza centres of GISN, WHO CC and academia

– Professionals at country level participating in technical networks (Ministries of Health, Public health agencies)

Thank you

谢谢Merci

Gracias