{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,16]],"date-time":"2026-05-16T07:24:24Z","timestamp":1778916264409,"version":"3.51.4"},"update-to":[{"DOI":"10.12688\/wellcomeopenres.19150.1","type":"new_version","label":"New version","source":"publisher","updated":{"date-parts":[[2023,11,27]],"date-time":"2023-11-27T00:00:00Z","timestamp":1701043200000}}],"reference-count":26,"publisher":"F1000 Research Ltd","license":[{"start":{"date-parts":[[2023,11,27]],"date-time":"2023-11-27T00:00:00Z","timestamp":1701043200000},"content-version":"tdm","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100006041","name":"Innovate UK","doi-asserted-by":"publisher","award":["971614"],"award-info":[{"award-number":["971614"]}],"id":[{"id":"10.13039\/501100006041","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100004440","name":"Wellcome","doi-asserted-by":"publisher","award":["220991"],"award-info":[{"award-number":["220991"]}],"id":[{"id":"10.13039\/100004440","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/100004440","name":"Wellcome","doi-asserted-by":"publisher","award":["203077"],"award-info":[{"award-number":["203077"]}],"id":[{"id":"10.13039\/100004440","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["wellcomeopenresearch.org"],"crossmark-restriction":false},"short-container-title":["Wellcome Open Res"],"abstract":"<ns4:p>Background There are limited data on the immunogenicity of coronavirus disease 2019 (COVID-19) vaccines in African populations. Here we report the immunogenicity and safety of the ChAdOx1 nCoV-19 (AZD1222) vaccine from a phase 1\/2 single-blind, randomised, controlled trial among adults in Kenya conducted as part of the early studies assessing vaccine performance in different geographical settings to inform Emergency Use Authorisation. Methods We recruited and randomly assigned (1:1) 400 healthy adults aged \u226518 years in Kenya to receive ChAdOx1 nCoV-19 or control rabies vaccine, each as a two-dose schedule with a 3-month interval. The co-primary outcomes were safety, and immunogenicity assessed using total IgG enzyme-linked immunosorbent assay (ELISA) against SARS-CoV-2 spike protein 28 days after the second vaccination. Results Between 28th October 2020 and 19th August 2021, 400 participants were enrolled and assigned to receive ChAdOx1 nCoV-19 (n=200) or rabies vaccine (n=200). Local and systemic adverse events were self-limiting and mild or moderate in nature. Three serious adverse events were reported but these were deemed unrelated to vaccination. The geometric mean anti-spike IgG titres 28 days after second dose vaccination were higher in the ChAdOx1 group (2773 ELISA units [EU], 95% CI 2447, 3142) than in the rabies vaccine group (61 EU, 95% CI 45, 81) and persisted over the 12 months follow-up. We did not identify any symptomatic infections or hospital admissions with respiratory illness and so vaccine efficacy against clinically apparent infection could not be measured. Vaccine efficacy against asymptomatic SARS-CoV-2 infection was 38.4% (95% CI -26.8%, 70.1%; p=0.188). Conclusions The safety, immunogenicity and efficacy against asymptomatic infection of ChAdOx1 nCoV-19 among Kenyan adults was similar to that observed elsewhere in the world, but efficacy against symptomatic infection or severe disease could not be measured in this cohort. Pan-African Clinical Trials Registration PACTR202005681895696 (11\/05\/2020)<\/ns4:p>","DOI":"10.12688\/wellcomeopenres.19150.2","type":"journal-article","created":{"date-parts":[[2023,11,27]],"date-time":"2023-11-27T05:08:57Z","timestamp":1701061737000},"page":"182","update-policy":"https:\/\/doi.org\/10.12688\/wellcomeopenres.crossmark-policy","source":"Crossref","is-referenced-by-count":7,"title":["Safety and immunogenicity of ChAdOx1 nCoV-19 (AZD1222) vaccine in adults in Kenya: a phase 1\/2 single-blind, randomised controlled 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status","group":{"name":"current-referee-status","label":"Current Referee Status"}},{"value":"10.21956\/wellcomeopenres.22625.r70571, Marianne W. Mureithi, Department of Microbiology, University of Nairobi, Nairobi, 02 May 2024, version 2, indexed","URL":"https:\/\/wellcomeopenresearch.org\/articles\/8-182\/v2#referee-response-70571","order":0,"name":"referee-response-70571","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"10.21956\/wellcomeopenres.22625.r70570, Dongming Zhou, Tianjin Medical University, Tianjin,, 08 Dec 2023, version 2, indexed","URL":"https:\/\/wellcomeopenresearch.org\/articles\/8-182\/v2#referee-response-70570","order":1,"name":"referee-response-70570","label":"Referee Report","group":{"name":"article-reports","label":"Article Reports"}},{"value":"This study was supported by Wellcome [220991, <a href=https:\/\/europepmc.org\/grantfinder\/grantdetails?query=pi%3A%22%7BProf%7D%7BLambe%7D%7BTeresa%7D%7BT%7D%22%20gid%3A%22220991%22%20ga%3A%22Wellcome%20Trust%22&cat=>https:\/\/doi.org\/10.35802\/220991<\/a> and 203077, <a href=https:\/\/doi.org\/10.35802\/203077>https:\/\/doi.org\/10.35802\/203077<\/a>], the University of Oxford, and Innovate UK (project 971614). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.","order":2,"name":"grant-information","label":"Grant Information"},{"value":"This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.","order":0,"name":"copyright-info","label":"Copyright"}]}}