National Influenza Sentinel Surveillance

Viet Nam: 2006-2012

Dr. Nguyen Thi Thu Yen

Coordinator, National Influenza Surveillance

National Institute of Hygiene and Epidemiology

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Organizational network of Institutes and sentinel sites

NITD, Hanoi

dAK LAK

tHAI BINH

HTD HCMc

PH #1 HCMC

BA TRIEU

Moh/CDC/who/NIHE

KHANH HOAINSTITUTEHIGHLANDS

PASTEUR HCMC

NIHE

Tt. HUE

LANG SON

HOA BINH

NPH

THANH XUAN

dONG NAI

TIEN GIANG

DA NANG CITYPASTEUR

NHATRANG

ILI CASE DEFINITION

Sudden onset of fever >38°C

• Cough and/or sore throat

• Absence of another diagnosis

• Illness onset within 3 days required in selection of cases for specimen collection and influenza testing

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ILI SURVEILLANCE METHODS

� Every day select first 2 ILI patients with illness onset within 3 days for investigation and throat swab collection at each site.

� Record total patients and ILI patients.

� Every week transport specimens to designated regional laboratory at each site.

� Test specimens for influenza by RT-PCR at regional laboratories.

� If PCR (+), subtyping and virus isolations will be done

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55

� For person ≥ 5 years old:–Meet ILI case definition (sudden onset of fever over 38°C, cough and/ or sore throat in the absence of other diagnosis), AND–Shortness of breath or difficulty breathing, AND–Requiring hospital admission.

� For children <5 years old:–Any child <5 years old with pneumonia or severe pneumonia, AND –Requiring hospital admission.

SARI CASE DEFINITION

SAMPLING METHOD FOR SARI SURVEILLANCE:• Based on number of SARI admitted in each hospital

per year, selected 30%

II. SARI Surveillance

Name of Sites Number of sampled SARI

Number of SARISelected per

week

National Pediatric Hospital 200 4

Khanh Hoa Hospital 400 8

Dak Lak Hospital 400 8

Hospital of Tropical Diseases HCMC 425 9

Pediatric Hospital #1 HCMC 200 4

Total 1625 33

77

SARI SENTINEL SITES, 2011-2012

* #1 Pediatric Hospital stopped in March 2012

� Every week select SARI cases with illness onset within 7 days for investigation and throat swab collection at each site.

� Record total patients and SARI patients.

� Transport specimens to regional laboratories.

� Test specimens for influenza by RT-PCR at regional laboratories.

� If PCR (+), subtyping and virus isolations will be done.

SARI SURVEILLANCE METHODS

SVP case definition:

� Sudden onset of fever > 38oC, AND

� Difficulty in breathing, AND

� Chest radiograph findings compatible with viral pneumonia, AND

� No alternative diagnosis, such as bacteria pneumonia or tuberculosis

SVP surveillance sites: 63 provinces

Surveillance methods:

� Case investigation

� Throat swab collection

� RT-PCR testing

SEVERE VIRAL PNEUMONIA (SVP) SURVEILLANCE

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ILI SURVEILLANCE

RESULTS

1010

Total and ILI outpatient visits by sentinel site

No. Sentinel Site

Total Number Number ILI Percent ILI

Patient Visits Patient Visits Visits (%)

1 NIITD, Hanoi 45738 852 1.9

2 Natl. Ped. Hosp., Hanoi 285271 81364 28.5

3 Ped. Hosp. #1, HCMC 300063 58210 19.4

4 Hosp. Trop. Dis., HCMC 230608 37924 16.4

5 Khanh Hoa Prov. Hospital 149934 23057 15.4

6 Dac Lac Prov. Hospital 162727 33914 20.8

7 Kien Xuong Dist. Hospital 703480 86193 12.3

8 Hoa Binh Dist. Hospital 111586 8443 7.6

9 Cao Loc Dist. Hospital 86172 6008 7.0

10 Huong Thuy Dist. Hospital 162238 5133 3.2

11 Ba Trieu Clinic, Hanoi 36944 3400 9.2

12 Thanh Xuan Clinic, Hanoi 66207 4058 6.1

13 Thanh Khe Dist. Hospital 278842 15782 5.7

14 Xuan Loc Dist. Hospital 519193 37777 7.3

15 Cai Be Dist. Hospital 505238 34655 6.9

All sentinel sites 3644241 436770 12.0 1111

RT-PCR positive ILI cases by sentinel site

No.Sentinel site

Number ILI

patients tested

Number (%) A/H1 positive

Number (%) A/H3 positive

Number (%) Influenza B

Number (%) pA/H1N1 2009

Other results (%)*

Total Number (%) Influenza

Positive

1 NIITD, Hanoi731 51 (7) 76 (10.4) 75 (10.3) 0(0) 4 (0.5) 206 (28.2)

2 Natl. Ped. Hosp., Hanoi2703 131 (4.8) 231 (8.5) 257 (9.5) 98 (3.6) 3 (0.1) 720 (26.6)

3 Ped. Hosp. #1, HCMC2648 130 (4.9) 211 (8) 151 (5.7) 111 (4.2) 0(0) 603 (22.8)

4 Hosp. Trop. Dis., HCMC2902 61 (2.1) 129 (4.4) 188 (6.5) 143 (4.9) 0(0) 521 (18)

5 Khanh Hoa Prov. Hospital3103 108 (3.5) 231 (7.4) 206 (6.6) 104 (3.4) 2 (0.1) 651 (21)

6 Dac Lac Prov. Hospital3051 65 (2.1) 132 (4.3) 187 (6.1) 86 (2.8) 3 (0.1) 473 (15.5)

7 Kien Xuong Dist. Hospital2908 80 (2.8) 143 (4.9) 246 (8.5) 58 (2) 3 (0.1) 530 (18.2)

8 Hoa Binh Dist. Hospital2080 102 (4.9) 135 (6.5) 88 (4.2) 41 (2) 0(0) 366 (17.6)

9 Cao Loc Dist. Hospital2719 95 (3.5) 119 (4.4) 159 (5.8) 63 (2.3) 2 (0.1) 438 (16.1)

10 Huong Thuy Dist. Hospt.1936 150 (7.7) 131 (6.8) 131 (6.8) 98 (5.1) 1 (0.1) 511 (26.4)

11 Ba Trieu Clinic, Hanoi1220 66 (5.4) 80 (6.6) 47 (3.9) (0) 2 (0.2) 195 (16)

12 Thanh Xuan Clinic, Hanoi2637 106 (4.0) 247 (9.4) 162 (6.1) 83 (3.1) 1 (0) 599 (22.7)

13 Thanh Khe Dist. Hospital2152 103 (4.8) 146 (6.8) 213 (9.9) 109 (5.1) 0 (0) 571 (26.5)

14 Xuan Loc Dist. Hospital2106 27 (1.3) 146 (6.9) 196 (9.3) 144 (6.8) 0 (0) 513 (24.4)

15 Cai Be Dist. Hospital2151 21 (1.0) 135 (6.3) 177 (8.2) 113 (5.3) 1(0) 447 (20.8)

All sites35047 1296 (3.7) 2292 (6.5) 2483 (7.1) 1251 (3.6) 22 (0.1) 7344 (21)

* 22 other positive results: A unsubtyped (7); AH1&B (2); A/H3&B (12); pA/H1N1&B (1) 1212

Influenza types/subtypes circulating in Viet Nam, 2006-2012 (N= 7344 positive)

0

5

10

15

20

25

30

35

40

45

Per

cent

Month - Year

A/H1 A/H3 B pA/H1N1/2009

1313

Seasonal Influenza Viruses Isolated in Vietnam, 2006- 2012

Year Number of specimens

#RT-PCR

(+)

(%)RT-PCR

(+)

Isolates (+)

Rate (%) positive

Isolates/RT-PCR

(+)

Isolates/Total

specimens

2006 4625 947 20.5 29 3.1 0.62007 6467 1167 18.0 117 10.0 1.82008 6974 1488 21.3 46 3.1 0.72009 7402 1943 26.2 133 6.8 1.8

2010 4405 979 22.2 74 7.6 1.7

2011 4416 645 14.6 88 13.6 2.0

2012 758 175 23.1 NA NA NA

Total 35047 7344 21.0 487 6.6 1.4

SARI surveillance Results

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Name of sitesTested SARI

B# (%)

A/H3N2# (%)

A/H5N1# (%)

pA/H1N1# (%)

Total Positive

# (%)

Dak Lak Hosp. 452 13 (2.9) 10 (2.2) 1 (0.3) 18 (3.9) 42 ( 9.3)

Khanh Hoa Hosp. 390 19 (4.9) 7 (1.8) (0) 8 (2.1) 34 (8.8)

Ped.Hosp #1 165 (0) 1 (0.6) (0) 2 (1.2) 3 (1.8)

Nat’l Ped. Hosp. 187 8 (4.3) (0) (0) 2 (1.1) 10 (5.4)

Hosp. Trop Diseases

384 23 (5.8) 6 (1.6) (0) 17 (4.4) 46 (11.8)

Total 1578 63 (3.9) 24 (1.5) 1 (0.1) 47 (2.9) 135 (8.4)

RT-PCR positive SARI cases, 2011-2012

PROPORTION OF INFLUENZA TYPES/SUBTYPES IN SARI CASES BY MONTH, 2011-2012 (N=135 POSITIVE)

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SVP surveillanceResults

1818

Results of SVP testing2006 – 2012

RT-PCR results

2006 2007 2008 2009 2010 2011 2012 Total

Negative 124 198 177 160 109 99 22 889

A/H5 0 8 6 5 7 0 4 30

A/H1 4 2 2 1 0 0 9

B 1 14 1 2 1 4 23

A/H3 0 6 0 10 4 0 20

pA/H1N1/2009 0 0 0 25 10 28 0 63

RSV 0 0 1 - - 0 0 1

Total (+) 5 16 23 42 23 29 8 146

Total cases 129 214 200 202 132 128 30 1035

Percent (+) % 3.9 7.5 11.1 20.8 17.4 22.7 26.7 14.01919

Proportion of Influenza virus type/subtypes in SVP Cases, 2006-2012 (n=145)

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Distributionof A/H5N1, 2006-2012

� # provinces: 18� # cases: 30

6/6/2012 21

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Achievements and challenges

� Achievements:

– Set up a national influenza surveillance network

– Standardized laboratory network, high quality performance in all

4 regional labs

– Monitored influenza virus types/subtypes circulating

– Obtained epidemiological and virological information on influenza

to guide control and prevention policies in country

– Contributed to global influenza surveillance and provided virusstrains for vaccine virus selection

� Challenges:

– System depends on external funds, need internal sustainable funds for long term.

– High turnover of surveillance staff, need regular training

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NIHE

THANK YOU!