The cost-effectiveness of using pneumococcal conjugate vaccine (PCV13) versus pneumococcal polysaccharide vaccine (PPSV23), in South African adults

Streptococcus pneumoniae (pneumococcus) remains an important cause of morbidity and mortality. Pneumococcal vaccination is part of the South African pediatric public immunization program but the potential cost-effectiveness of such an intervention for adults is unknown. This study aimed to compare the cost-effectiveness of two widely used pneumococcal vaccines: pneumococcal conjugate vaccine (PCV13) and pneumococcal polysaccharide vaccine (PPSV23) in South African adults, 18 years and older. Four analyses were carried out in a) both the private and public health care sectors; and b) for the HIV-infected population alone and for the total mixed population (all HIV-infected and -uninfected people). A previously published global pharmacoeconomic model was adapted and populated to represent the South African adult population. The model utilized a Markov-type process to depict the lifetime clinical and economic outcomes of patients who acquire pneumococcal disease in 2015, from a societal perspective. Costs were sourced in South African rand and converted to US dollar (USD). The incremental cost divided by the incremental effectiveness (expressed as quality-adjusted life years gained) represented the incremental cost-effectiveness ratio for PCV13 compared to PPSV23. Results indicated that the use of PCV13 compared to PPSV23 is highly cost-effective in the public sector cohorts with incremental cost-effectiveness ratios of $771 (R11,106)/quality-adjusted life year and $956 (R13,773)/quality-adjusted life year for the HIV-infected and mixed populations, respectively. The private sector cohort showed similar highly cost-effective results for the mixed population (incremental cost-effectiveness ratio $626 (R9,013)/quality-adjusted life year) and the HIV-infected cohort (dominant). In sensitivity analysis, the model was sensitive to vaccine price and effectiveness. Probabilistic sensitivity analyses found predominantly cost-effective ICERs. From a societal perspective, these findings provide some guidance to policy makers for consideration and implementation of an immunization strategy for both the public and private sector and amongst different adult patient pools in South Africa.