Modeling the impact of a partially effective HIV vaccine on HIV infection and death among women and infants in South Africa

Objective: To assess the potential impact over 10 years of a partially effective HIV vaccine in a cohort of 15-year-old adolescent girls in South Africa in terms of HIV infections and deaths prevented in mothers and infants. Methods: A computer simulation was constructed using a population of all 15-year-old adolescent girls in South Africa followed for 10 years. A partially effective vaccine is introduced into this population with the ability to reduce the HIV incidence rates of the adolescents and vertical transmission to their infants through birth and breast-feeding. At the end of this 10 year period, the number of HIV infections and death prevented in adolescents and infants is analyzed. Results: Using a 5% HIV incidence rate, a 50% effective vaccine decreases the number of HIV cases among adolescents by 57,653 (28.7%) and the number of cases among infants by 13,765 (28.9%) over 10 years. In addition, assuming a vaccine cost of $20 per dose, the vaccination program can save approximately $120 million for the South African government over 10 years. Conclusion: A partially effective HIV vaccine has an important role in HIV prevention in adolescents and infants in South Africa irrespective of other public policy implementations.