Original Research

High immunity and low mortality after Omicron and mass event in Cameroon despite low vaccination

Yap Boum II, Lucrece Matchim, Dominique K. Guimsop, Bongkiyung D. Buri, Lisa M. Bebell, Yuya S.F. Jaudel, Fai K.G. Njuwa, Daniel B. Danirla, Eric Youm, Rodrigue Ntone, Claudric Roosevelt Tchame, Dora Tchiasso, Rachelle Essaka, Justin B. Eyong, Audrey Ngosso, Herwin Nanda, Nsaibirni R. Fondze, Mark Ndifon Ndifon, Lucrèce Eteki, Yonta F.C. Ghislain, Bruno Yannick Eyenga Messi, Hamadou Moustapha, Moustafa Hamdja, René Ghislain Essomba, Nadia Mandeng, Tamakloe A.K. Modeste, Anne-Cécile Zoung-Kani Bisseck, Sara Irène Eyangoh, Richard Njouom, Marie Claire Okomo, Linda Esso, Epee Emilienne, Georges-Alain Etoundi Mballa
Journal of Public Health in Africa | Vol 15, No 1 | a649 | DOI: https://doi.org/10.4102/jphia.v15i1.649 | © 2024 Boum II Y, Matchim L, Guimsop DK, et al. | This work is licensed under CC Attribution 4.0
Submitted: 01 June 2024 | Published: 07 November 2024

About the author(s)

Yap Boum II, Public Health Emergency Operation Center, Ministry of Public Health, Yaoundé, Cameroon; Epicentre, Yaoundé, Cameroon; and Faculty of Biomedical Medicine and Science, University of Yaoundé I, Yaoundé, Cameroon
Lucrece Matchim, Epicentre, Yaoundé, Cameroon
Dominique K. Guimsop, Department for the Control of Disease, Epidemics and Pandemics, Ministry of Public Health, Yaoundé, Cameroon; and Western Africa Regional Coordination Center, Africa Centers for Disease Control, Abuja, Nigeria
Bongkiyung D. Buri, Epicentre, Yaoundé, Cameroon
Lisa M. Bebell, Department of Medicine, Massachusetts General Hospital, and Harvard Medical School, Boston, Massachusetts, United States
Yuya S.F. Jaudel, Epicentre, Paris, France
Fai K.G. Njuwa, Epicentre, Yaoundé, Cameroon
Daniel B. Danirla, Epicentre, Yaoundé, Cameroon
Eric Youm, Epicentre, Paris, France
Rodrigue Ntone, Epicentre, Yaoundé, Cameroon
Claudric Roosevelt Tchame, Department for the Control of Disease, Epidemics and Pandemics, Ministry of Public Health, Yaoundé, Cameroon
Dora Tchiasso, Epicentre, Yaoundé, Cameroon
Rachelle Essaka, Laboratoire du Lac, Yaoundé, Cameroon
Justin B. Eyong, Epicentre, Yaoundé, Cameroon
Audrey Ngosso, Epicentre, Yaoundé, Cameroon
Herwin Nanda, Epicentre, Yaoundé, Cameroon
Nsaibirni R. Fondze, Epicentre, Paris, France
Mark Ndifon Ndifon, Epicentre, Paris, France
Lucrèce Eteki, Epicentre, Yaoundé, Cameroon
Yonta F.C. Ghislain, Epicentre, Yaoundé, Cameroon
Bruno Yannick Eyenga Messi, Epicentre, Yaoundé, Cameroon
Hamadou Moustapha, Epicentre, Yaoundé, Cameroon
Moustafa Hamdja, Epicentre, Yaoundé, Cameroon
René Ghislain Essomba, National Public Health Laboratory, Yaoundé, Cameroon
Nadia Mandeng, Public Health Emergency Operation Center, Ministry of Public Health, Yaoundé, Cameroon
Tamakloe A.K. Modeste, Médecins Sans Frontières Suisse, Yaoundé, Cameroon
Anne-Cécile Zoung-Kani Bisseck, Health Operations Research Division, Ministry of Public Health, Yaoundé, Cameroon
Sara Irène Eyangoh, Centre Pasteur du Cameroon, Yaoundé, Cameroon
Richard Njouom, Centre Pasteur du Cameroon, Yaoundé, Cameroon
Marie Claire Okomo, National Public Health Laboratory, Yaoundé, Cameroon
Linda Esso, Public Health Emergency Operation Center, Ministry of Public Health, Yaoundé, Cameroon; and Department for the Control of Disease, Epidemics and Pandemics, Yaoundé, Cameroon
Epee Emilienne, Public Health Emergency Operation Center, Ministry of Public Health, Yaoundé, Cameroon; and Department for the Control of Disease, Epidemics and Pandemics, Ministry of Public Health, Yaoundé, Cameroon
Georges-Alain Etoundi Mballa, Public Health Emergency Operation Center, Ministry of Public Health, Yaoundé, Cameroon; and Department for the Control of Disease, Epidemics and Pandemics, Ministry of Public Health, Yaoundé, Cameroon

Abstract

Background: Little is known about the evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunity in African communities.

Aim: We evaluated changes in anti-SARS-CoV-2 antibodies, mortality and vaccination status in Cameroon between August 2021 and September 2022 to begin describing the evolution of the pandemic in Africa.

Setting: The study was conducted across Cameroon’s 10 regional capitals, between 2021 and 2022 as the country hosted a mass gathering.

Methods: We conducted a cross-sectional population-based survey in 2022, including SARS-CoV-2 seroprevalence testing and retrospective mortality estimation using two-stage cluster sampling. We estimated and compared seroprevalence and crude mortality rates (CMR) to a survey conducted in 2021 using the same methodology.

Results: We performed serologic testing on 8400 individuals and collected mortality data from 22 314 individuals. Approximately 5% in each survey reported SARS-CoV-2-vaccination. Rapid diagnostic test-based seroprevalence increased from 11.2% (95% confidence interval [CI]: 10–12.5) to 59.8% (95% CI: 58.3–61.2) between 2021 and 2022, despite no increase in the proportion vaccinated. The CMR decreased from 0.17 to 0.06 deaths per 10 000 persons per day between 2021 and 2022. In 2022, no deaths were reportedly attributable to COVID-19 as compared to 17 deaths in 2021.

Conclusion: Over a 12-month period encompassing two waves of omicron variant SARS-CoV-2 and a mass gathering, SARS-CoV-2 seropositivity in Cameroon approached 60%, and deaths declined despite low vaccination coverage.

Contribution: This study challenges the assumption that high immunisation coverage is the sole determinant of epidemic control in the African context and encourages policymakers to increasingly rely on local research when designing response strategies for more effective outbreak management.


Keywords

seroprevalence; SARS-CoV-2; mortality; immunity; Africa.

Sustainable Development Goal

Goal 3: Good health and well-being

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