Vaccine Preventable Disease Surveillance: Overview
Thomas Cherian, WHO
Global Framework on Immunization Monitoring and Surveillance (GFIMS)
l An extension of the GIVS, published on December 07 - http://www.who.int/immunization/en/
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
Type of surveillance needs to be aligned to surveillance objectives
Example Objective Surveillance characteristics
Polio, measles Document eradication/elimination -find all chains of transmission; certification
Country-wide, active, with lab confirmation of all cases
Syndromic surveillance, avian influenza
Routine monitoring; outbreak detection investigation
Country-wide passive, aggregate reporting, with selective investigation
Meningitis, Invasive bacterial diseases, rotavirus
Networks of sentinel sites providing representative data for the population
Sentinel site surveillance
Hepatitis B; disease incidence based on regular home visits
Obtain epidemiological information Epidemiologic studies (detailed, labour intensive) and sero-surveys
Yes (182 countries or 94%) No (13 countries or 6%)
Countries Implementing Case-based Measles Surveillance, 2010
Source: WHO/IVB database, November 2011
Global VPD Laboratory Network, N~ 700 Labs
Polio and measles/rubella (109) Measles/rubella only (531)
Measles/rubella and yellow fever (14) Polio, Measles/rubella and yellow fever (13)
Labs/Institutes testing for: Polio only (23)
+ 331 (Prefecture Labs)
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 2009. All rights reserved
No data reported
B2
B3
D4
D5
D8
D9
H1
Incidence:(per 100'000)
<0.1
≥0.1 - <1
≥1 - <5
≥5
Genotypes:West Africa inset West Europe & Middle East inset
6
1
Chart proportional tonumber of genotypes
d11
G3
Distribution of measles genotypes, 2010
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 2011. All rights reserved.
Distribution of Measles Genotypes 2010
Laboratory confirmed measles but no sequences reported N=45
Acknowledgements: LabNet, P Chenoweth, O Beauvais
0
500,000
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2,500,000
1980
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Number of cases Official coverage WHO/UNICEF estimates
Source: WHO/IVB database, 2011 193 WHO Member States. Data as of September 2011
Pertussis global annual reported cases and DTP3 coverage, 1980-2010
Sero surveys for documenting impact of Hep B vaccination
Comparison of HBsAg Rate between 1992 and 2006 By Age, in China
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
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).
• Centers of excellence • Specialized epidemiologic studies to complement surveillance
Supported by laboratory network
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)
Vaccine impact evaluation in Malawi Trends in bacterial meningitis incidence, 1997-2005
• Data provided by PBM Network, WHO-Malawi and Queen Elizabeth Hospital, Blantyre, Malawi.
• AMP analysis
Introduction of Hib vaccine: February 2002
0
10
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30
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1997 1998 1999 2000 2001 2002 2003 2004 2005
Incidence (per 100,000 per year)
Hib Blantyre City
Hib Blantyre rural
Sp Blantyre City
Sp Blantyre rural
Impact of Hib vaccine: based only on case counts
Lewis et al. Bull WHO 2008; 86:292-301
Using non-denominator based surveillance data: case control studies
Lewis et al. Bull WHO 2008; 86:292-301
Types of sentinel surveillance Bridging to get more comprehensive data
Facility-based Meningitis
Facility-based; All invasive bacterial diseases
Population-based
Vaccine clinical trials (probe)
Surveillance Research
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
Thank you
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
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
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
MNT not eliminated
MNT eliminated prior to 2000 MNT eliminated since 2000
Source: WHO/UNICEF data base as of October 2011.
Over 100 million women reached with at least 2 TT doses from 1999 - 2010