National Influenza Surveillance System in Vietnam

Detect outbreaks? • Monitor strains? • Determine seasonality? • Contribute to vaccine strains? • Understand virology: evolution, resistance, vaccine matching? • Determine epi: target prevention measures? • Define clinical spectrum? • Understand burden: disease, economic?

National Influenza Surveillance

System in Vietnam (NISS)

Ngo Huy Tu, MD, MPM

Epidemiology Department National Institute of Hygiene and Epidemiology

Surveillance

Systematic collection, analysis, interpretation

and dissemination of information for use in

public health action

Why sentinel surveillance?

as an early warning, but:

What are the goals of the

surveillance?

matching?

Number of ILI cases in Vietnam, 2004 – 2015

(Data from national communicable diseases surveillance system)

Influenza surveillance in Vietnam

surveillance and no laboratory-enhanced active sentinel surveillance

Severe Acute Respiratory Infection (SARI)

Influenza-Like Illness (ILI)

Venn diagram of respiratory illnesses

Viral

Influenza

Bacterial

Pyramid of influenza virus infections

Asymptomatic Mild symptoms, no medical care

Mild symptoms, outpatient care

Severe symptoms, inpatient care

ICU Death

Severity

Attempted to be detected by:

Pyramid within pyramid

represents (re)emerging

influenza virus with

pandemic potential SARI and SVP

surveillance

ILI surveillance

Household surveys

Serology studies

Sentinel Influenza surveillance System in

Vietnam

General Objective

To collect the necessary epidemiological and virological

information to guide influenza prevention and control policies and activities Gradually establish the nationwide influenza

surveillance network in Vietnam

Specific Objectives

1 Describe epidemiological, virological characteristics and Monitor

influenza virus strains circulating in Vietnam Introduce influenza virus strains for vaccination

2 To detect avian influenza viruses including emerging strain such

as A/H5N1, A/H7N9 and outbreak potential re-assortment of

influenza virus genomes and mutation

3 Gradually establish the nationwide influenza surveillance

network in Vietnam to guide influenza prevention and control policies and activities

4 Contribute in FLunet (Global Influenza Surveillance and Response

System) and WHO Collaborating Centers

Selecting sites

1 Is geographically representative

2 Has a high density of population, high level of commercial and cultural exchanges

3 Urban and rural coverage

4 Sentinel surveillance is based in health facilities that already have the necessary infrastructure, equipment, and trained staff

5 Has close collaboration in specimens and data collection

6 Has the ability to preserve specimens at the proper temperature and easy transport specimens to the laboratory

7 Is a commitment and willingness to participate

8 Ability to long term maintained surveillance activities

For ILI: Admits a large number of ILI patients (at least 50 patients/week)

ILI Surveillance sites, 2006-2015

16 sites: 7 in the northern; 3 in the central; 1 High plateau; 4 in the southern

ILI Cases Definitions

Influenza-like illness (ILI)

Criteria for sample collection

within 3 days

– For ILI:

 2 first cases/site/day every 5 working day

 Sample: throat swabs is priority

– ILI sample is tested in Regional Institutes

14

Data collection Methods

ILI TIME IMPLEMENTATION, 2006-2015

Selected ILI results (cumulative)

Cumulative results in period 2006 to 2015

Rate of positive of Influenza A and B by month

Rate of positive ILI samples by influenza subtype by

Rate of positive ILI samples by age group and by year

Distribution of positive samples by gender and virus

sub-type, 2013-2015

50.7 49.3

A/H1N1

53.3 46.7

B

51.4 48.6

A/H3N2

51.8 48.2

Tổ g số +

50.5 49.5

A/H1N1 pdm

• B, A/H1N1, A/H3N2, and A/H1N1-pdm rotational

circulation and cause outbreak, among those B and

A/H3N2 are mainly subtype influenza B (35,9%) and

Selecting sites

1 Is geographically representative

2 Has a high density of population, high level of commercial and cultural exchanges

3 Urban and rural coverage

4 Sentinel surveillance is based in health facilities that already have the necessary infrastructure, equipment, and trained staff

5 Has close collaboration in specimens and data collection

6 Has the ability to preserve specimens at the proper temperature and easy transport specimens to the laboratory

7 Is a commitment and willingness to participate

8 Ability to long term maintained surveillance activities

For ILI: Admits a large number of ILI patients (at least 50 patients/week)

For SARI: Is a centre for diagnosis and treatment of severe acute respiratory diseases

SARI Surveillance sites (2010 – 2015)

23

BV B ạ ch Mai

SARI Definitions

Severe Acute Respiratory Infection (SARI)

For children < 5 years:

• Cough or difficult breathing AND

• Any one of the following:

– Breathing > 60/min for ages <2m

– Breathing > 50/min for ages 2m to < 1yr – Breathing > 40/min for ages 1 to < 5 years – Chest indrawing

– Stridor in a calm child

– Unable to drink or breast feed

– Vomits everything

– Convulsions

– Lethargic or unconscious

– Oxygenation saturation < 90%

SARI Definitions

Severe Acute Respiratory Infection (SARI)

– For SARI:

 5 – 8 cases/site/week

 Sample: throat swabs is priority, otherwise nasal

or bronchial fluid is considered

SARI SURVEILLANCE RESULTS, 2011-2015

• Total patients visit: 228.656

• Total SARI: 37.541 (16% in total admissions patients)

• Total SARI sample collected for testing: 5.148

• Total SARI sample tested using RT-PCR: 5.148

• Total SARI samples positive with influenza 611 (11,9%)

PROPORTION SARI/TOTAL ADMISSION AND PROPORTION

SARI SAMPLE POSITIVE WITH INFLUENZA ,2011-2015

28

0 1000 2000 3000 4000 5000 6000 7000 8000 9000

Distribution of SARI patients by region and aetiologies,

2011-2015

Region Total samples No positive A/H1N1/09

(%) A/H3N2 (%)

B (%) A/H3&B (%)

DISTRIBUTION OF POSITIVE RATE WITH FLUENZA BY MONTH AND YEAR

Distribution of influenza viruses by time,

DISTRIBUTION OF SARI BY AGE GROUP

• Proportion of SARI/Total Admission: 16.5%

• Influenza viruses account for 12% SARI patients There were two picks in March and June

• Age group 0 – 4 years old account more than 50% SARI patients

CONCLUSION

Case definitions for SARI Surveillance

2016 - 2017

– SARI (using WHO case definition 2014):

• For SARI:

 10 cases/site/week

 Sample: throat swabs and nasal swabs; or

tracheal fluid replaced

SARI Sentinel sites, 2016-2017

Time of implementation

TT

2 B ệ nh vi ệ n Nhi Trung

3

4

5

6 B

7 B ệ nh vi ệ n Trung

8

9

10 ớ i Tp HCM

11

12

13

CDC support WHO support

Distribution of influenza on SARI

Region Samples Influenza positive A/ H1N1/pdm A/ H3N2 B

Other influenza virus

Distribution of 7 non influenza viruses on SARI

No HMPV Adeno P1 P2 P3 RSV Rhino Co-infection

# # % # % # % # % # % # % # % # %

Miền

Bắc 926 23 2.5% 46 5.0% 32 3.5% 5 0.5% 42 4.5% 127 13.7% 100 10.8% 53 5.7%Miền

SEVERE PNEUMONIA SURVEILLANCE

(SVP SURVEILLANCE)

6/20/2017 41

Objective

1 To early detect avian influenza (A/H5N1, A/H7N9)

on human and new strains of influenza viruses

2 To describe characteristic and circulation of

influenza viruses on SVP patients

6/20/2017 42

SVP case definition

• Sudden onset of fever > 38oC (measured at consultation room or reported)

• Difficult breathing (determined by rapid respiratory

rate, shortness of breath or blood oxygen/

carbondioxide saturation level)

• Chest X-ray consistent with viral pneumonia

• No suspect diagnoses of other aetiology such as

bacterial pneumonia, tuberculosis etc were made by

specialist conference

6/20/2017 43

Surveillance sites

– Passive surveillance system at all

hospitals in 63 provinces

Methods

– Sampled, epidemiological and clinical data collected on form for all SVP cases

– Data and samples sent to regional lab

– All specimens will be tested in laboratories of 4 regional institutes using RT-PCR

– Standardized Laboratory Management in Lab network

Distribution of SVP cases by aetiologies, 2006-2015

Lab results 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Total

Influenza A(H5N1) virus in Vietnam,

• Influenza viruses account for 16.9% SVP patients

• Early detect avian influenza A/H5N1 in the period 2006-2014 33/34 (97%) avian influenza A/H5N1 cases were detected through SVP surveillance system

• In Vietnam, not yet found any cases of influenza A(H7N9) in humans

CONCLUSION

ACHIEVEMENTS OF NATIONAL INFLUENZA

SURVEILLANCE SYSTEM

 Establishment of the National Influenza Surveillance System

 Provide epidemiological and virological information on all strains of human influenza in Vietnam through active surveillance

 Detect outbreaks of Avian Influenza in Human by Passive surveillance for Viral Pneumonia (SVP)

 Contribute to national influenza prevention and control, especially

Strengthen Public Health Laboratory Networks

 Sharing influenza isolates for Vaccine candidates of Northern

ADVANTAGES

 Advantage of support from MOH, GDPM, district and

provincial PMC, sentinel hospital, US.CDC representatives

 Standardized Laboratory Networks, high quality performance and stability in all 4 regions

 Enthusiastic staffs, dynamic, professional and technical

mastery

 Effectiveness of the system to provide timely information to contribute to guide influenza prevention and control policies and activities

CHALLENGES

 System depends on outside funding, needs for long term with stable financial source to maintain and further strengthen the system

 At provincial level, laboratory testing to confirm viruses

unavailable, test result is always late to be useful for on time intervention and treatment

 High costs of biological testing products, there is no

standardized estimating procedures and SOP for an effective management of biological products

 Settlement and contract’s signatures was made late on

scheduled activities

Thank You For Your Attention!