To Register      SMDM Homepage

Sunday, 17 October 2004

This presentation is part of: Poster Session - Public Health; Methodological Advances

MARKOV MODEL OF A PARTIALLY-EFFECTIVE HIV VACCINE ON ADOLESCENT WOMEN IN SOUTH AFRICA

Sam Amirfar, MD, Jim Hollenberg, MD, and Salim Abdool Karim, MD, PhD. Weill Medical College of Cornell University, Department of Internal Medicine, New York, NY

Purpose: To assess a partially-effective HIV vaccine in a cohort of 15-year old adolescent women in South Africa over 10 years in terms of HIV infections and deaths prevented in mothers and infants.

Methods: A Markov model is constructed for all 15-year old adolescents in South Africa followed for 10 years. Each adolescent can become HIV infected, pregnant, or die. This model’s baseline output without the vaccine is calibrated with the AIDS demographic model used by the Actuarial Society of South Africa. A vaccine is introduced to reduce the HIV incidence rates of adolescents as well as vertical transmission to their infants through birth and breastfeeding. At the end of 10 years, the number of HIV infections and death prevented in adolescents and infants is analyzed with a Monte Carlo simulation. In addition, when an adolescent becomes pregnant or develops AIDS, she has a probability of starting prophylactic antiretrovirals or starting highly active antiretrovirals (HAART).

Results (cohort of 500,000): If in four years South Africa were to adopt the use of prophylactic antiretrovirals to prevent mother-to-child transmission in the peripartum period, an additional 31% of infant infections are prevented at 1 year. If the majority of AIDS patients have access to HAART by 2008, the number of HIV-related deaths would dramatically drop (77%) but the number of adolescents living with HIV would increase (7%). In this setting, a 50% effective vaccine would not prevent deaths but decrease the number of adolescents ever infected by HIV by 65,160 (15%) and HIV-infected infants by 19,150 (23%).

Conclusion: A partially-effective HIV vaccine consistently lowers the number of infected adolescents and infants by an additional 15-20% in our model in addition to the advantages gained from antiretrovirals. A partially-effective HIV vaccine has an important role in HIV prevention of adolescents and infants in South Africa no matter the domestic policy implemented.


See more of Poster Session - Public Health; Methodological Advances
See more of The 26th Annual Meeting of the Society for Medical Decision Making (October 17-20, 2004)