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Modeling vaccination strategies for developing countries

Modeling vaccination strategies for developing countries. DIMACS meeting May 17-20, 2004 Annelies Van Rie. Childhood mortality. More than 10 million deaths that occur globally in children age < 5 2002: millenium goals: reduce childhood mortality by two thirds by 2015.

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Modeling vaccination strategies for developing countries

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  1. Modeling vaccination strategies for developing countries DIMACS meeting May 17-20, 2004 Annelies Van Rie

  2. Childhood mortality • More than 10 million deaths that occur globally in children age < 5 • 2002: millenium goals: reduce childhood mortality by two thirds by 2015. • 1990: 180/1000 in sub-Saharan Africa • 1990: 9/1000 in industrialized countries • 2000: 175/1000 in sub-Saharan Africa • 2000: 6/1000 in industrialized countries • Neonatal disorders and infectious diseases are the important causes

  3. Black et al(Lancet, 2003) prediction for 42 countries contributing 90% of CH deaths Neonatal disorders: 33% (29-36) Diarrhea: 22% (14-30) Pneumonia: 21% (14-24) Malaria: 9% (6-13) AIDS: 3% Measles: 1% (1-9%) 2000 WHO estimates prediction for all WHO member states Neonatal disorders: 42% Diarrhea: 13% Pneumonia: 19% Malaria: 9% AIDS: 3% Measles: 5% Global causes of child deaths • a substantial proportion (24%) are caused by vaccine preventable infections (Lara Wolfson)

  4. Vaccines for children • Vaccines are one of the grand successes of the 21st century. • The impact has been substantially larger in the developed word • Vaccines have been developed to preferentially address the epidemiology of infectious diseases in high income countries • Malaria (9%) • Meningococcal (type C scale 2 logs less compared to type A)

  5. Childhood vaccination: 2 worlds or many more? • Double standard or 1 standard • Rotavirus • Thiomersal • polio • Disease burden in developing countries vs disease burden in developed countries • How do can we help countries in determining priorities? • Capacity building (human, laboratory) • Country typology

  6. Black et al. Lancet 2003;361:2226

  7. Barriers to use of existing childhood vaccines • Lack of disease burden data • Need of cold chain • Poor transportation and storage systems • Inadequate and poorly motivated HCW • Budget constraints • Lack of political will Obaro et al. Vaccine 2003

  8. Barriers to use of “new” vaccines • Lack of disease burden data • Budget constraints • Lack of political will

  9. Improving vaccine use in developing countries (1) • Advocate its use • Generation of local burden of disease data (disease surveillance systems, regional sentinel sites) • Demonstration of immunogenicity, efficacy and safety in the local population • Cost effectiveness data (1 vaccine or comparisons?) • Inform policy makers, opinion leaders and HCW • Inform the community through mass media

  10. Improving vaccine use in developing countries (2) • Pay for its use (GAVI) • Immunization Systems Strengthening (ISS) support –performance/reward based system • New Vaccine Support (NVS) – vaccine provided for 1st five years

  11. Improving vaccine use in developing countries (3) • Decrease costs of vaccines (local production) • Develop easy to use vaccines (no cold chain) • Decrease the number of dosages • Pertussis: elimination of 1 childhood dose • Hib : 3 dose instead of 4 in UK • Pneumococcal vaccine: 1 dose instead of 4? • Italy: 26% coverage 1-year olds plus 31-53% catch up gives 91% reduction in invasive Hib disease (Gallo et al. Vaccine 2002) • US: largest decrease in invasive disease in 65+ (Whitney at el. NEJM 2003) • Fractional dose • Hepatitis B: 10-fold dilution with equivalent Ab avidity in South African study (Lagos et al, Lancet 1998) Obaro et al. Vaccine 2003

  12. Improving vaccine use in developing countries (4) • Targeted vaccination • Who to vaccinate? • Importance of unvaccinated pockets? • Importance of differences between rural and urban? • WAIFW differences? • Acquaintance immunization (Cohen et al. Physical Review letters 2003) • Vaccination of randomly selected acquintances of randomly selected persons • Large Household vaccination (Ball et al. Ann Appl Prob. 1997) • Vaccinees chosen sequentially from those households with the largest number of susceptibles

  13. Improving vaccine use in developing countries (5) • Targeted vaccination • PLACE based vaccination: not WHO but WHERE • Limitation of contact tracing in infectious disease control • Identification of geographic clustering and high transmission areas (HTA) for HIV • Role of locations in transmission of infectious disease: TB transmission in bar, restaurant, dancing hall, church, crack house, rock concert, prison, shelters in developing countries, piqueras in Mexico and shebeens in SA

  14. PLACE • Priorities for Local AIDS Control Efforts • AIDS prevention programs should focus on places where people with high rates of new sexual partnership formation meet new sexual partners • Available demographic and epidemiologic contextual data help to identify places where individuals with highest rates of new partnership formation meet new partners; • To minimize bias, the method does not primarily rely on self-reported behavior, contact tracing, naming of sexual partners, or require information about self-reported behavior except to validate information obtained in other ways; • The method is feasibly implemented in a short period of time without outside technical experts • The method provides program indicators useful for intervention monitoring. Weir et al. Sex Transm Inf 2002

  15. PLACE for HIV and TB (method) • Township in Cape Town, South Africa and in Kinshasa, Democratic Republic of Congo. • Selection of PLACE venues likely to have a high HIV incidence of infection based on epidemiological, socio-demographic and behavioral information via key informants • site visits, site interviews • Information was on TB symptoms (Cape Town) and presence of active TB (Kinshasa).

  16. PLACE for HIV and TB (results) • 3482 persons interviewed for risk behavior and TB symptoms. • Chronic cough was present in • Cape Town (221 PLACE venues) : • 15% of 621 men • 12% of 356 women • Kinshasa (63 PLACE venues) • 15% of 948 men • 11% of 245 women • Kinshasa ( 7 STI clinics) • 11.5% of 69 male and 8% of 234 female clients • Kinshasa (2 ANC clinics) • 2.4 % of 1035 pregnant women. • 15 (9%) of 163 Kinshasa participants reporting chronic cough, had active TB confirmed by bacteriological methods • HIV infection: STI > PLACE venues >> ANC

  17. PLACE for HIV and TB (use) • Prevention efforts • Education • Condom distribution • Diagnosis • VCT • TB • Intervention ? • STI syndromatic treatment • TB treatment DOT • HIV treatment DOT

  18. PLACE for VACCINATION • Focus on places where forces of infection are highest • Use available demographic and epidemiologic contextual data to identify areas most likely to have high forces of infection

  19. Conclusion • To reduce childhood mortality we need action now • Traditional advocacy methods have been slow and small in effect • GAVI has sustainability issues • Value of innovative ideas: can modeling help?

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