Optimizing pneumococcal prevention in South African older adults: Cost-effectiveness of PCV20 versus PPSV23 in the context of HIV-associated risk.

Pneumococcal disease remains a major cause of morbidity and mortality among older adults in South Africa, particularly among people living with HIV. Evidence on the cost-effectiveness of Prevnar 20 (PCV20) vs. Pneumovax 23 (PPSV23) vaccine in this setting remains limited. This study was conducted to evaluate the cost-effectiveness of PCV20 compared with PPSV23 vaccine among adults aged ≥65y in South Africa, and to assess the impact of HIV stratification on economic outcomes. A static decision-tree model was developed from the South African public healthcare payer perspective. The analysis incorporated invasive pneumococcal disease, pneumococcal community-acquired pneumonia, quality-adjusted life-years, maximum acceptable price, and 5y budget impact. HIV-stratified incidence and CD4-adjusted vaccine effectiveness were included. In the general population, PCV20 provided greater health benefits than PPSV23 but was not cost-effective at the current base-case price (USD 20.00/dose), with an ICER of USD 17,323/QALY. Price was the main driver of cost-effectiveness. In contrast, targeted vaccination of older adults living with HIV was economically favorable, with an ICER of USD 2,104/QALY under national incidence assumptions, and even stronger results in high-burden settings. The cost-effectiveness of PCV20 in South Africa is contingent upon the price of vaccine and risk-based targeting. Vaccinating all older adults universally may not be cost-effective at current prices, suggesting that targeted vaccination of older adults with HIV represents a more efficient strategy.