Public health impact of COVID-19 vaccination and economic implications in Ghana and Benin: a mathematical modelling and cost-effectiveness study

Background: The outbreak of SARS-CoV-2 has led to numerous cases and deaths globally. Ghana and Benin are two Africa countries which prioritized vaccination, introducing them as early as March 2021 alongside non-pharmaceutical interventions (NPIs) to mitigate the epidemiological and socio-economic impact of COVID-19. This study quantified the impact of vaccination coverage on cases, deaths averted, hospital resources, and economic impacts compared to a scenario without vaccination. Methods: This study adopted the COVID-19 International Modelling Consortium (CoMo) model to estimate COVID-19 transmission dynamics, disease burden, and the impact of vaccination scenarios accounting for NPIs at varying intensity. We assessed the impact of COVID-19 vaccination programs by estimating additional cases and deaths averted if no vaccines were distributed. We assumed a 78% vaccine efficacy and conducted sensitivity analyses by varying vaccination coverage targets above the 20% set by COVAX and 40% by WHO by the end of 2022. A cost-effectiveness analysis of COVID-19 vaccination in Ghana and Benin was conducted from societal and health system perspectives. Our analysis considered vaccination coverage target of 20% - 80%. Results: Vaccinating approximately 40% of the population in Ghana and Benin, as recommended by WHO, would reduce the total predicted reported cases from 1.6% (95% CrI: 1.1, 1.9) to 0.7% (95% CrI: 0.6, 1.3) and avert additional 3585 (95% CrI: 1793-4066) and 33 COVID-19 deaths between April 2020 to December 2022. For reported+unreported cases, it would reduce from 35.3% (95% CrI: 20.5, 43.7) to 18.8% (95% CrI: 13, 33) in Ghana and from 1.5% (95% CrI: 0.4, 8.1) to 1.0% (95% CrI: 0.5, 15.3) in Benin. In both countries, at 40% vaccination coverage compared to no vaccination, vaccination is cost-effective from both health system and societal perspectives. Also, in Ghana vaccination up to 70% coverage is still cost-effective from the societal perspective. In Benin, any coverage beyond 40% of the population was not cost-effective. Conclusion: Higher vaccine coverage alone, does not necessarily lead to greater health or economic benefits. The cost-effectiveness of increasing COVID-19 vaccine coverage is influenced by coverage rates, national context and scope of costs considered. Overall, vaccination is only cost-effective when it is done together with adherence to COVID-19 prevention guidelines, and that should be the priority of policymakers for the two countries.