Post-Omicron SARS-CoV-2 antibody prevalence in Sierra Leone: A cross-sectional, nationally representative, follow-up serosurvey

• DOI: 10.1371/journal.pgph.0004273
• Publication Date: 2025-04-16T17:27:01Z
• Authors: Smit Chitre; Mohamed Bailor Ba...; Joseph Sam Kanu; Theophilus S. Conteh; Mohamed Bayoh; Matilda N. Kamara; Haja Fatmata Bangura; Jonathan S. Lascher; Raphael Frankfurter; Sarah A. Goldberg; David V. Glidden; J. Daniel Kelly; Sulaiman Lakoh; Eugene T. Richardson
• Keywords: Seroprevalence; Pandemic; Cross-sectional study

Based on a serosurvey conducted in March 2021, Barrie and colleagues published the first nationally representative SARS-CoV-2 Africa, estimating seroprevalence of 2.6% Sierra Leone, 43 times higher than reported number cases at that time. Over following two years, increasingly transmissible variants—specifically Delta Omicron—proliferated across globe, their impact Africa is poorly understood. Additional data are therefore necessary to understand pandemic’s progression continent for evaluating containment measures future preparedness. Our follow-up survey was Leone from February 2023. We returned 120 Enumeration Areas throughout country collecting blood samples one or more individuals per household as well information sociodemographic characteristics, history COVID-19 infection immunization, attitudes towards vaccination. The weighted overall (vaccinated and/or infection) >19 years age 33% (95% CI 29–37). Using distributions our previous serosurvey, predicted (any prior general population 28% 15–41). ~11 pre-Delta/Omicron prevalence. It also over 300 cases. Despite this, low compared with countries Europe Americas (pointing lower transmission Leone). In addition, results suggest regarding prevention campaigns claiming have vaccinated 70% adults December 2022: 1) they resulted limited seroconversion; 2) there significant waning immunity; 3) many less were reported. Regardless cause, utility Vaccine Delivery Partnership (CoVDP) efforts three into pandemic called question.