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Original Research – Special Collection: Vaccine Effectiveness in Africa
COVID-19 severity and vaccine effectiveness in Malawi: A test-negative case-control study
Submitted: 15 August 2024 | Published: 11 April 2025
About the author(s)
Clara Sambani, Public Health Institute of Malawi, Lilongwe, MalawiVictor Chikwapulo, World Health Organization, Malawi Office, Lilongwe, Malawi
Regina Mankhamba, Public Health Institute of Malawi, Lilongwe, Malawi
Tonny Muwonge, Global Health Security Department, Infectious Diseases Institute, Makerere University, Kampala, Uganda
Mavuto Thomas, Health Education Division, Ministry of Health, Lilongwe, Malawi
Baxter Salatiel, Public Health Institute of Malawi, Lilongwe, Malawi
Edna Mandala, School of Maternal, Neonatal and Reproductive Health, Kamuzu University of Health Sciences, Lilongwe, Malawi
Leah Mbabazi, Department of Global Health Security, Infectious Diseases institute, Makerere University, Kampala, Uganda
Suzan Nakasendwa, Department of Global Health Security, Infectious Diseases institute, Makerere University, Kampala, Uganda
Rodgers R. Ayebare, Department of Global Health Security, Infectious Diseases institute, Makerere University, Kampala, Uganda
Collins Mitambo, Public Health Institute of Malawi, Lilongwe, Malawi
Matthew Kagoli, Public Health Institute of Malawi, Lilongwe, Malawi
Mabvuto Chiwaula, Public Health Institute of Malawi, Lilongwe, Malawi
Dzinkambani Kambalame, Public Health Institute of Malawi, Lilongwe, Malawi
Triza Chirwa, Public Health Institute of Malawi, Lilongwe, Malawi
Liness Chinyamunyamu, Dowa District Hospital, Ministry of Health, Lilongwe, Malawi
Tamrat Shaweno, Directorate of Research and Innovation, Africa Centres for Disease Control and Prevention, Addis Ababa, Ethiopia
Nebiyu Dereje, Directorate of Research and Innovation, Africa Centres for Disease Control and Prevention, Addis Ababa, Ethiopia
Tajudeen Raji, Directorate of Research and Innovation, Africa Centres for Disease Control and Prevention, Addis Ababa, Ethiopia
Francis Kakooza, Department of Global Health Security, Infectious Diseases Institute, Makerere University, Lilongwe, Uganda
Mosoka P. Fallah, Directorate of Research and Innovation, Africa Centres for Disease Control and Prevention, Addis Ababa, Ethiopia
Evelyn C. Banda, Public Health Institute of Malawi, Lilongwe, Malawi
Abigail Kazembe, School of Maternal, Neonatal and Reproductive Health, Kamuzu University of Health Sciences, Lilongwe, Malawi; and African Forum for Research and Education in Health, Kumasi, Ghana
Mitch Matoga, University of North Carolina Project, Lilongwe, Malawi
Abstract
Background: COVID-19 vaccines were administered globally, and Malawi commenced vaccination on 11 March 2021.
Aim: This study assessed the real-world effectiveness of COVID-19 vaccines and factors associated with disease severity and mortality in Malawi.
Setting: A facility-based case-control study within the largest referral hospitals.
Methods: Cases (COVID-19 positive) were matched 1:1 with controls based on age, sex and testing date. Interviews via phone focused on COVID-19 testing and vaccination, underlying conditions and disease outcomes. Analysed using STATA 17, the exposure of interest was vaccination status. For vaccine effectiveness (VE), conditional logistic regression modelling was used, while disease severity and management were analysed using binary logistic regression.
Results: The unvaccinated were at 53.3%, and 35.8% were fully vaccinated and/or received a booster. The VE among the fully and partially vaccinated was 10% (95% CI: –26.2, 35.81) and 31.8% (95% CI: –9.91, 57.72), respectively compared to the unvaccinated. Most of the COVID-19 patients (87.8%) were not hospitalised. Underlying chronic conditions and a previous positive COVID-19 test were associated with severe disease (aOR: 3.54, 95% CI: 1.65, 7.61 and aOR: 2.73, 95% CI: 1.13, 7.61, respectively); however, these odds were not different by vaccination status.
Conclusion: The VE was low and severe disease was linked with chronic illnesses and previous positive COVID-19 tests. Efforts to promote vaccination through education and access should be enhanced, particularly for those with underlying chronic conditions.
Contribution: The findings can inform strategies on prioritisation for disease vaccination and improving patient outcomes.
Keywords
Sustainable Development Goal
Metrics
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