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