Modeling infections and deaths averted due to COVID-19 vaccination strategies in Ghana

Abstract

This study assessed the impact of various COVID-19 vaccination strategies on health outcomes in Ghana using an age-stratified compartmental model. The population was stratified into three age groups: <25 years, 25-64 years, and 65+ years. Five vaccination optimization scenarios were explored, assuming that one million persons could be vaccinated in three versus six months. We also performed uncertainty analysis by assuming that the available doses were halved and doubled. The vaccine optimization strategies were assessed for the initial strain, followed by a sensitivity analysis for the delta variant by varying the reproduction number and vaccine efficacy. The results showed that vaccinating individuals <65 years was associated with the lowest cumulative infections when one million persons were vaccinated over three months for both the initial strain and the delta variant. On the contrary, prioritizing the elderly (65+) was associated with the lowest cumulative deaths for both strains.

Priority age targets for COVID-19 vaccination in Ethiopia under limited vaccine supply

“…The second pandemic phase that we consider mirrors the SARS-CoV-2 transmission dynamics after the launch of the national vaccination program in March 2021, when students were regularly receiving in-person education 31 . To account for the replacement of the ancestral lineages by the Delta variant of SARS-CoV-2 likely occurred in mid 2021 39 , we calibrate the transmission rate parameter in such a way to obtain an R 0 = 6 in absence of interventions and population immunity, based on published estimates [40][41][42][43][44] ; alternative values of R 0 are explored for sensitivity analysis. Model estimates of the natural immunity acquired by different age groups during the first pandemic phase are used to initialize the immunological status of the population in this second phase.…”