National Influenza Sentinel National Influenza Sentinel Surveillance Surveillance
Viet Nam: 2006-2007Viet Nam: 2006-2007
US CDC Collaboration and WHO Global US CDC Collaboration and WHO Global
Surveillance Network PartnershipSurveillance Network Partnership
Nguyen Thanh Chung, MD,Nguyen Thanh Chung, MD,
NIHENIHE
National reports of ILINational reports of ILI1996-20051996-2005
General objectivesGeneral objectives
Obtain epidemiological and Obtain epidemiological and virological information to guide virological information to guide influenza prevention and control influenza prevention and control policies and activitiespolicies and activities
Establish a sustainable national Establish a sustainable national influenza surveillance network in influenza surveillance network in VietnamVietnam
Specific ObjectivesSpecific Objectives
Determine influenza impact and Determine influenza impact and seasonality seasonality
Rapidly detect outbreaksRapidly detect outbreaks
Monitor circulating strains Monitor circulating strains
Contribute to influenza prevention and Contribute to influenza prevention and controlcontrol
Contribute to global surveillance and Contribute to global surveillance and selection of virus strains for vaccine selection of virus strains for vaccine productionproduction
OrganizationOrganization
NIHERegional Institutes
VAPMPMCs
MOHSentinel Sites
CDC/WHOpartners
OrganizationalOrganizationalnetwork ofnetwork ofInstitutes andInstitutes andsentinel sitessentinel sites
NIITD
dAK LAK
tHAI BINH
HCMc TDH
HCMC PH #1
BA TRIEU
Moh/CDC/who/NIHE
KHANH HOATAY
NGUYEN
HCMC
NIHE
Tt. HUE
LANG SON
HOA BINH
NPH
THANH XUAN
dONG NAI
TIEN GIANG
DA NANG CITYNHATRANG
Sentinel site Sentinel site characteristics characteristics
Major ecological regions represented Adult and pediatric populations served Different levels of health services
• Central referral hospitals• Provincial hospitals• District hospitals• Polyclinics / health centers
Case definition ILI (WHO)Case definition ILI (WHO)
Sudden onset of fever >38°CSudden onset of fever >38°C
Cough and/or sore throatCough and/or sore throat
Absence of another diagnosisAbsence of another diagnosis
Onset illness within 3 days Onset illness within 3 days for cases selected for PCR for cases selected for PCR testingtesting
ILI surveillance methodsILI surveillance methods
Total patient and ILI consultations recorded weekly at each site
First 2 ILI patients each day sampled for investigation
Throat swab collected and transported to regional laboratory
RT-PCR testing at regional laboratories
Virus sub-typing and isolations made if PCR +
ILI surveillance
Results
Total and ILI outpatient visits by sentinel site
No. Sentinel SiteTotal NumberPatient Visits
Number ILIPatient Visits
Percent ILIVisits (%)
01 NIITD, Hanoi 27713 775 2,8
02 Natl. Ped. Hosp., Hanoi 251664 75938 30,2
03 Ped. Hosp. #1, HCMC 154042 13127 8,5
04 Hosp. Trop. Dis., HCMC 108210 19862 18,4
05 Khanh Hoa Prov. Hospital 34189 10447 30,6
06 Dac Lac Prov. Hospital 42246 11172 26,4
07 Kien Xuong Dist. Hospital 259065 32099 12,4
08 Hoa Binh Dist. Hospital 38703 2863 7,4
09 Cao Loc Dist. Hospital 23009 1563 6,8
10 Huong Thuy Dist. Hospital 60770 1776 2,9
11 Ba Trieu Clinic, Hanoi 20200 1544 7,6
12 Thanh Xuan Clinic, Hanoi 23555 1422 6
13 Thanh Khe Dist. Hospital 31988 2263 7,1
14 Xuan Loc Dist. Hospital 52920 3230 6,1
15 Cai Be Dist. Hospital 51635 6440 12,5
All sentinel sites 1179909 184521 15,6
Sites no. 08, 09, 11 and 12 initiated surveillance on June, 1st 2006Sites no. 13, 14, and 15 initiated surveillance on June, 1st 2007
RT-PCR positive ILI cases, by sentinel sitesRT-PCR positive ILI cases, by sentinel sites
No. Sentinel site
Number ILI patients tested
Number (%)A/H1 positive
Number (%)A/H3 positive
Number (%) A undeter-mined
Number (%) Influenza Bpositive
Number (%) total InfluenzaPositive
01 NIITD, Hanoi 622 47 (7.6) 56 (9) 0 63 (10.1) 166 (26.7)
02 Natl. Ped. Hosp., Hanoi 869 76 (8.7) 97 (11.2) 1 69(7.9) 243(28.0)
03 Ped. Hosp. #1, HCMC 1000 69(6.9) 90(9.0) 0 77(7.7) 236(23.6)
04 Hosp. Trop. Dis., HCMC 999 39(3.9) 23(2.3) 0 52(5.2) 114(11.4)
05 Khanh Hoa Prov. Hospital 1000 53(5.3) 88(8.8) 2 56(5.6) 199(19.9)
06 Dac Lac Prov. Hospital 1001 27(2.7) 63(6.3) 0 62(6.2) 152(15.2)
07 Kien Xuong Dist. Hospital 1000 37(3.7) 58(5.8) 0 59(5.9) 154(15.4)
08 Hoa Binh Dist. Hospital 801 54(6.7) 71(8.9) 0 12(1.5) 137(17.1)
09 Cao Loc Dist. Hospital 682 42(6.2) 43(6.3) 0 12(1.8) 97(14.2)
10 Huong Thuy Dist. Hospt. 835 55(6.6) 81(9.7) 0 44(5.3) 180(21.6)
11 Ba Trieu Clinic, Hanoi 628 40(6.4) 60(9.6) 0 14(2.2) 114(18.2)
12 Thanh Xuan Clinic, Hanoi 778 43(5.5) 105(13.5) 0 12(1.5) 160(20.6)
13 Thanh Khe Dist. Hospital 309 8(2.6) 47(15.2) 0 14(4.5) 69(22.3)
14 Xuan Loc Dist. Hospital 278 0(0.0) 33(11.9) 0 25(9.0) 58(20.9)
15 Cai Be Dist. Hospital 280 0(0.0) 19(6.8) 0 14(5.0) 33(11.8)
All sites 11082 590(5.3) 934(8.4) 3 585(5.3) 2112(19.1)
Sites no. 08, 09, 11 and 12 initiated surveillance on June, 1st 2006Sites no. 13, 14, and 15 initiated surveillance on June, 1st 2007
19.917.2
20.9
15.2
0
5
10
15
20
25
30(%)
North South Central Highlands
Influenza percent Influenza percent positive by regionpositive by region
0
5
10
15
20
25
30
35
40
Jan. 0
6
Mar
. 06
May
. 06
Jul.
06
Sep. 0
6
Nov. 0
6
Jan. 0
7
Mar
. 07
May
. 07
Jul.
07
Sep. 0
7
Nov. 0
7
Po
siti
ve (
%)
A (H1N1) B A (H3N2)
Influenza types/subtypes circulating inInfluenza types/subtypes circulating inViet Nam, 2006-2007 Viet Nam, 2006-2007
(N=2112 virus detections)(N=2112 virus detections)
Percent of ILI testing positive for influenza A/H1N1, by month and region
0
10
20
30
40
50
60
70
Jan-0
6
Mar
-06
May
-06
Jul-0
6
Sep-0
6
Nov-06
Jan-0
7
Mar
-07
May
-07
Jul-0
7
Sep-0
7
Nov-07
Po
sit
ive
(%
)
Nothern Central Coastal Central Highland Southern
H1N1 subtype, 2007H1N1 subtype, 2007Results of SequencingResults of Sequencing
H1N1 subtype in 2007 had 99% H1N1 subtype in 2007 had 99% homology with homology with A/Solomon A/Solomon Islands/3/2006Islands/3/2006 subtype subtype
H1N1 subtypes isolated in Vietnam H1N1 subtypes isolated in Vietnam were homologous with the subtype were homologous with the subtype selected for flu vaccine production in selected for flu vaccine production in 20072007
Percent of ILI testing positive for influenza A/H3N2, by month and region
0
10
20
30
40
50
60
70
80
Jan-0
6
Mar
-06
May
-06
Jul-0
6
Sep-0
6
Nov-06
Jan-0
7
Mar
-07
May
-07
Jul-0
7
Sep-0
7
Nov-07
Po
sit
ive
(%
)
Nothern Central Coastal Central Highland Southern
H3N2 subtype, 2007H3N2 subtype, 2007
H3N2 subtype in 2007 showed 99% H3N2 subtype in 2007 showed 99% sequencing homology with sequencing homology with A/California/UR06-0463/2007 subtypeA/California/UR06-0463/2007 subtype
H3N2 subtypes isolated in 2007 in H3N2 subtypes isolated in 2007 in Vietnam differed from the subtype Vietnam differed from the subtype used for flu vaccine production in used for flu vaccine production in 2007.2007.
Percent of ILI testing positive for influenza B, by month and region
0
10
20
30
40
50
60
70
80
90
Ja
n-0
6
Fe
b-0
6
Ma
r-0
6
Ap
r-0
6
Ma
y-0
6
Ju
n-0
6
Ju
l-0
6
Au
g-0
6
Se
p-0
6
Oc
t-0
6
No
v-0
6
De
c-0
6
Ja
n-0
7
Fe
b-0
7
Ma
r-0
7
Ap
r-0
7
Ma
y-0
7
Ju
n-0
7
Ju
l-0
7
Au
g-0
7
Se
p-0
7
Oc
t-0
7
No
v-0
7
De
c-0
7
Po
siti
ve (
%)
Northern Central Coastal Central highland Southern
B flu virus subtype, 2007B flu virus subtype, 2007
B subtype in 2007 showed 99% B subtype in 2007 showed 99% sequencing homology with sequencing homology with B/Florida/02/2006 subtypeB/Florida/02/2006 subtype
B subtypes isolated in Vietnam in B subtypes isolated in Vietnam in 2007 were homologous with the 2007 were homologous with the virus used for vaccine production virus used for vaccine production in 2007.in 2007.
ILI results summaryILI results summary
ILI is a major health care burdenILI is a major health care burden High proportion ILI cases are influenzaHigh proportion ILI cases are influenza Influenza detected all times of year, in all Influenza detected all times of year, in all
regions, at all sitesregions, at all sites All common subtypes endemicAll common subtypes endemic Seasonal fluctuations occur in subtype Seasonal fluctuations occur in subtype
activityactivity Regional synchrony subtype activity Regional synchrony subtype activity
observedobserved
ChallengesChallenges Achieve greater efficiency, sustainabilityAchieve greater efficiency, sustainability
Apply results to policies and practicesApply results to policies and practices
Capabilities strengthening needed all levelsCapabilities strengthening needed all levels
Strengthen lab and epidemiology ties Strengthen lab and epidemiology ties
Strengthen links human and animal sectorsStrengthen links human and animal sectors
Increase scientific collaborations, Increase scientific collaborations, publicationspublications
Increase role in WHO Global NetworkIncrease role in WHO Global Network
Thank You
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