Modeling the potential public health impact of different vaccination strategies with an adapted vaccine in South Africa.

Background: COVID-19 vaccines adapted to newly emerging circulating variants are necessary to better protect the population due to the evolving nature of the SARS-CoV-2 virus.

Research design and methods: The South African population was stratified by age and risk (defined by comorbidities such as diabetes, obesity, smoking, cancer, and asthma), and HIV status. The outcomes of different vaccination strategies based on age, risk, and HIV status were estimated using a Markov-decision tree model based on age-specific inputs derived from the literature and South African surveillance data.

Results: Vaccinating older adults and those with comorbidities was estimated to avert 111,179 infections 18,281 hospitalizations, and 3,868 deaths, resulting in savings of ZAR 1,260 million (USD 67 million) and ZAR 3,205 million (USD 170 million) in direct and indirect costs, respectively. Similar results were obtained when considering strategies targeting older adults and the HIV population. Expanding vaccination to 75% of the standard-risk population prevented more infections (401%), hospitalizations (167%), and deaths (67%) and increased the direct (232%) and indirect (455%) cost savings compared to the base case.

Conclusions: Implementing widespread vaccination strategies that utilize a vaccine adapted to the prevailing circulating variant in South Africa would result in significant public health and economic gains.