Real-world COVID-19 vaccine effectiveness in Zimbabwe: A test-negative case-control study.

Background: COVID-19 vaccination is critical in sub-Saharan Africa to reduce the disease burden. This study assessed real-world vaccine effectiveness (VE) in Zimbabwe. Aim: To determine COVID-19 VE and factors associated with disease severity and mortality in Zimbabwe. Setting: The study setting comprised a test-negative case-control study across health facilities in Harare and Bulawayo (May 2023 - August 2023). Methods: Adults (≥ 18 years) were recruited from COVID-19 registers (1:1 case-control; matched by sex, age and clinic visit date). Telephone interviews assessed vaccination status, disease severity (cases) and comorbidities. Conditional logistic regression estimated VE (1 - odds ratio*100), with stratification by age and comorbidities. Ordinal and simple logistic regression analysed factors associated with disease severity and vaccination-variant relationships. Results: Overall vaccination coverage was 38% (fully vaccinated including boosters), with 62% unvaccinated. The median age was 38 years (interquartile range [IQR]: 30-50) with more females ( Conclusion: This study found a moderate VE of COVID-19 vaccines in Zimbabwe, potentially influenced by age, comorbidities and variants. We highlight the need for targeted vaccination strategies and public health measures informed by these findings. Contribution: This research informs public health strategies to optimise vaccination efforts and improve health outcomes across Africa, aligning with the journal's focus on public health issues.