Vaccine Preventable Disease Surveillance: Overview. Thomas Cherian, WHO

Transcription

1 Vaccine Preventable Disease Surveillance: Overview Thomas Cherian, WHO

2 Global Framework on Immunization Monitoring and Surveillance (GFIMS) l An extension of the GIVS, published on December l Outlines a vision for immunization monitoring and VPD surveillance Developed by WHO in collaboration with its global partners Call for integration of surveillance and monitoring systems Strengthening capacity at country level Emphasizes data quality assurance l Target/Audience Organizations that provide funding & support to immunization & surveillance activities Country level health planners & decision-makers

3 Type of surveillance needs to be aligned to surveillance objectives Surveillance characteristics Country-wide, active, with lab confirmation of all cases Country-wide passive, aggregate reporting, with selective investigation Sentinel site surveillance Epidemiologic studies (detailed, labour intensive) and sero-surveys Objective Document eradication/elimination -find all chains of transmission; certification Routine monitoring; outbreak detection investigation Networks of sentinel sites providing representative data for the population Obtain epidemiological information Example Polio, measles Syndromic surveillance, avian influenza Meningitis, Invasive bacterial diseases, rotavirus Hepatitis B; disease incidence based on regular home visits

4 Countries Implementing Case-based Measles Surveillance, 2010 Yes (182 countries or 94%) No (13 countries or 6%) Source: WHO/IVB database, November 2011

5 Global VPD Laboratory Network, N~ 700 Labs (Prefecture Labs) Labs/Institutes testing for: Polio only (23) Measles/rubella only (531) Polio and measles/rubella (109) Measles/rubella and yellow fever (14) Polio, Measles/rubella and yellow fever (13) The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement. WHO All rights reserved

6 Distribution of measles genotypes, 2010 Distribution of Measles Genotypes 2010 West Africa inset West Europe & Middle East inset Genotypes: Incidence: (per 100'000) B2 <0.1 B <1 d <5 D4 5 D5 No data reported D8 D9 G3 Chart proportional to number of genotypes 6 H1 1 Acknowledgements: LabNet, P Chenoweth, O Beauvais Laboratory confirmed measles but no sequences reported The boundaries and names shown and the designations used on this map do not imply the expression of any opinion whatsoever on the part of the World Health Organization concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers N=45 or boundaries. Dotted lines on maps represent approximate border lines for which there may not yet be full agreement.

7 Pertussis global annual reported cases and DTP3 coverage, ,500, number of cases 2,000,000 1,500,000 1,000, , immunization coverage (%) Number of cases Official coverage WHO/UNICEF estimates Source: WHO/IVB database, WHO Member States. Data as of September 2011

8 Sero surveys for documenting impact of Hep B vaccination Comparison of HBsAg Rate between 1992 and 2006 By Age, in China

9 Surveillance for new vaccines Based on detection and investigation of selected disease syndromes Meningitis (Hib, pneumococcus, meningococcus, others) Pneumonias (Hib, pneumococcus, virus, others) Community acquired sepsis (pneumococcus, non-typhi salmonella, typhoid, others) Diarrhoea (rotavirus, ETEC, shigella) Sentinel site surveillance Selected sites capturing suspect cases/syndromes Selection of sites may depend on disease, population representativeness, laboratory capacity Case ascertainment is usually facility-based, with or without defined catchment population

10 Surveillance Structure "Tiered approach" Not financially and operationally feasible to expect all sites to conduct all various surveillance activities. Surveillance structure considering a "tiered approach": Hospital sentinel sites "core sites": meningitis and rotavirus surveillance. 1 per country, in larger countries up to 3 sites. Additional select sites "enhanced sites": Sepsis, pneumonia and other invasive disease surveillance. 1 sites for every 3 countries. Population-based sites to generate incidence estimates: 1 one site per region (6 Regions + 3 AFRO sub-regions). Supported by laboratory network Centers of excellence Specialized epidemiologic studies to complement surveillance

11 Types of sentinel site surveillance l Population-based laboratory surveillance (defined denominator) Gold standard Provides incidence rates Can estimate cases of disease caused by pathogen Useful for monitoring impact of vaccine Monitor serotype replacement l Facility-based surveillance (no denominator) Documents pathogen as a cause of severe disease Proportion of disease syndrome caused by pathogen Age distribution Serotype prevalence Antimicrobial resistance Case fatality ratios (for hospitalized cases)

12 Vaccine impact evaluation in Malawi Trends in bacterial meningitis incidence, Introduction of Hib vaccine: February 2002 Incidence (per 100,000 per year) Hib Blantyre City Hib Blantyre rural Sp Blantyre City Sp Blantyre rural Data provided by PBM Network, WHO-Malawi and Queen Elizabeth Hospital, Blantyre, Malawi. AMP analysis

13 Impact of Hib vaccine: based only on case counts Lewis et al. Bull WHO 2008; 86:

14 Using non-denominator based surveillance data: case control studies Lewis et al. Bull WHO 2008; 86:

15 Types of sentinel surveillance Bridging to get more comprehensive data Facility-based Meningitis Facility-based; All invasive bacterial diseases Populationbased Vaccine clinical trials (probe) Surveillance Research

16 Summary l Polio and measles surveillance have provided a platform for surveillance for VPDs Can be used to add on other diseases requiring country-wide surveillance Detection of epidemics l While aggregate reporting has been continuing for many years, quality of reporting needs improvement Sub national data to monitor programme performance Pick up atypical cases, e.g. pertussis in young infants and older individuals l Sentinel site surveillance for invasive bacterial diseases and rotavirus diarrhoea being established, but need more work Detailed presentation to follow

17 Thank you

18 Sentinel site surveillance l Has been incremental progress with establishing a sustained surveillance system, through MOH, for diseases targeted by new vaccines Quality & yield needs improvement for IBD l Country ownership Personnel and infrastructure External funding to maintain quality, standards and coordination l Sentinel site surveillance systems have their limitations, even with improvement in quality Need to complemented with special more intensive surveillance projects l Caution with over-interpretation of data from sentinel surveillance Need a minimal number of isolates and years of observation

19 Questions to SAGE l Support the idea of sentinel site surveillance as proposed? Alternative is to revert to only conducting time-limited project type surveillance l Agree with the proposed steps to improve surveillance quality for IBD? l WHO role in supporting surveillance? Will require resources to perform this role

20 21 Countries* eliminated MNT between 2000 & 2011 *(Plus 15 States out of 33 in India, Ethiopia part and 29 provinces out of 33 in Indonesia) leaving 38 countries yet to eliminate MNT Over 100 million women reached with at least 2 TT doses from MNT eliminated prior to 2000 MNT eliminated since 2000 MNT not eliminated Source: WHO/UNICEF data base as of October 2011.