The Case for Adolescent HIV Vaccination in South Africa: A Cost-Effectiveness Analysis

Abstract

Despite comprising 0.7% of the world population, South Africa is home to 18% of the global human immunodeficiency virus (HIV) prevalence. Unyielding HIV subepidemics among adolescents threaten national attempts to curtail the disease burden. Should an HIV vaccine become available, establishing its point of entry into the health system becomes a priority. This study assesses the impact of school-based HIV vaccination and explores how variations in vaccine characteristics affect cost-effectiveness. The cost per quality adjusted life year (QALY) gained associated with school-based adolescent HIV vaccination services was assessed using Markov modeling that simulated annual cycles based on national costing data. The estimation was based on a life expectancy of 70 years and employs the health care provider perspective. The simultaneous implementation of HIV vaccination services with current HIV management programs would be cost-effective, even at relatively higher vaccine cost. At base vaccine cost of US$ 12, the incremental cost effectiveness ratio (ICER) was US$ 43 per QALY gained, with improved ICER values yielded at lower vaccine costs. The ICER was sensitive to duration of vaccine mediated protection and variations in vaccine efficacy. Data from this work demonstrate that vaccines offering longer duration of protection and at lower cost would result in improved ICER values. School-based HIV vaccine services of adolescents, in addition to current HIV prevention and treatment health services delivered, would be cost-effective.

FIGURE 1

Semi-Markov model of the human immunodeficiency virus (HIV) vaccine strategy. Healthy vaccinated and unvaccinated individuals may enter into a HIV positive state. They can progress from a HIV infection state to the HIV treatment pool. All states may progress to a death states at a rate specific to the state they were currently in.

FIGURE 2

The cost-effectiveness plane. The incremental costs and effects were represented visually using the incremental cost-effectiveness plane. The x-axis divides the plane according to incremental cost (positive above, negative below), while the y-axis divides the plane according to incremental effect (positive to the right, negative to the left). The axes divide the incremental cost-effectiveness plane into 4 quadrants through the origin. All values falling below the WTP threshold indicted are cost-effective.

FIGURE 3

Cost-effectiveness acceptability curve. The CEAC shows the proportion of simulations that would be cost-effective (y-axis) given different threshold values of cost per QALY gained (x-axis). CEAC = cost effective acceptability curve, QALY = quality adjusted life year.