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

Area of Science:

• Public Health
• Epidemiology
• Vaccinology

Background:

• COVID-19 vaccination is crucial for reducing disease burden in sub-Saharan Africa.
• This study evaluated the real-world vaccine effectiveness (VE) of COVID-19 vaccines in Zimbabwe.

Purpose of the Study:

• To determine the COVID-19 VE in Zimbabwe.
• To identify factors associated with disease severity and mortality post-vaccination.

Main Methods:

• A test-negative case-control study was conducted in Harare and Bulawayo from May to August 2023.
• Adults (≥18 years) were recruited, with vaccination status and comorbidities assessed via telephone interviews.
• Conditional logistic regression analyzed VE, while ordinal and simple logistic regression examined factors influencing severity and variant relationships.

Main Results:

• Overall VE against any COVID-19 infection was 32.2% (95% CI: 8.9, 49.5).
• Vaccination coverage was 38% (fully vaccinated including boosters); 62% were unvaccinated.
• Older age (45+ years) and chronic conditions correlated with higher hospitalization risk. Hospitalization and mortality rates among cases were 34.8% and 11.6%, respectively.

Conclusions:

• COVID-19 vaccines demonstrated moderate VE in Zimbabwe, influenced by factors like age, comorbidities, and circulating variants.
• Findings emphasize the need for tailored vaccination strategies and public health interventions to enhance vaccine impact and improve health outcomes in the region.