News Release

Analysis of seroprevalence in Kenya suggests virus exposure more extensive than reported

Peer-Reviewed Publication

American Association for the Advancement of Science (AAAS)

Researchers analyzing blood samples from blood donors across Kenya estimate that by June 2020, when many COVID-19 deaths were expected in the country but hadn't occurred at such scale, 4.3% of Kenyans had antibodies to the virus. This suggests SARS-CoV-2 exposure has been more extensive than indicated by case-based surveillance in Kenya, the authors say. Their results will help guide the pandemic response in a region where economic effects of lockdown - including for the way it disrupts routine medical care to women and children - have proven particularly debilitating. Africa accounts for 17% of the global population but by late July 2020, despite evidence of several months of SARS-CoV-2 transmission, it accounted for only 5% of the global COVID-19 cases and 3% of the global COVID-19 deaths. In Kenya, the first case of SARS-CoV-2 was reported in mid-March 2020, followed quickly by the institution of lockdowns. By end of July, however, national surveillance recorded 20,636 cases and 341 deaths in Kenya - an increase notably slower than the epidemic in parts of China, Europe and the United States. Seeking to understand this pattern, Sophie Uyoga and colleagues conducted one of the first field-based seroprevalence surveys in Africa. They analyzed samples collected from more than 3,000 blood transfusion donors from late April to mid-June 2020. Using a highly specific assay, the authors report a crude seroprevalence of 5.6% in this group. Adjusting for the age-sex structure of Kenya, the authors estimate an overall seroprevalence of 4.3%, peaking in younger age groups, which is consistent with other studies. The authors offer several potential explanations for why Kenya has seen relatively lower cases and deaths even as SARS-CoV-2 exposure appears considerable, including the steep demographic age-pyramid in Kenya, which results in a smaller vulnerable age group. The results of their study, say the authors, support "the impression that disease may be attenuated in Africa."


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