PLOS Global Public Health (Jan 2022)

SARS-CoV-2 seroprevalence in three Kenyan health and demographic surveillance sites, December 2020-May 2021.

  • Anthony O Etyang,
  • Ifedayo Adetifa,
  • Richard Omore,
  • Thomas Misore,
  • Abdhalah K Ziraba,
  • Maurine A Ng'oda,
  • Evelyn Gitau,
  • John Gitonga,
  • Daisy Mugo,
  • Bernadette Kutima,
  • Henry Karanja,
  • Monica Toroitich,
  • James Nyagwange,
  • James Tuju,
  • Perpetual Wanjiku,
  • Rashid Aman,
  • Patrick Amoth,
  • Mercy Mwangangi,
  • Kadondi Kasera,
  • Wangari Ng'ang'a,
  • Donald Akech,
  • Antipa Sigilai,
  • Boniface Karia,
  • Angela Karani,
  • Shirine Voller,
  • Charles N Agoti,
  • Lynette I Ochola-Oyier,
  • Mark Otiende,
  • Christian Bottomley,
  • Amek Nyaguara,
  • Sophie Uyoga,
  • Katherine Gallagher,
  • Eunice W Kagucia,
  • Dickens Onyango,
  • Benjamin Tsofa,
  • Joseph Mwangangi,
  • Eric Maitha,
  • Edwine Barasa,
  • Philip Bejon,
  • George M Warimwe,
  • J Anthony G Scott,
  • Ambrose Agweyu

DOI
https://doi.org/10.1371/journal.pgph.0000883
Journal volume & issue
Vol. 2, no. 8
p. e0000883

Abstract

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BackgroundMost of the studies that have informed the public health response to the COVID-19 pandemic in Kenya have relied on samples that are not representative of the general population. We conducted population-based serosurveys at three Health and Demographic Surveillance Systems (HDSSs) to determine the cumulative incidence of infection with SARS-CoV-2.MethodsWe selected random age-stratified population-based samples at HDSSs in Kisumu, Nairobi and Kilifi, in Kenya. Blood samples were collected from participants between 01 Dec 2020 and 27 May 2021. No participant had received a COVID-19 vaccine. We tested for IgG antibodies to SARS-CoV-2 spike protein using ELISA. Locally-validated assay sensitivity and specificity were 93% (95% CI 88-96%) and 99% (95% CI 98-99.5%), respectively. We adjusted prevalence estimates using classical methods and Bayesian modelling to account for the sampling scheme and assay performance.ResultsWe recruited 2,559 individuals from the three HDSS sites, median age (IQR) 27 (10-78) years and 52% were female. Seroprevalence at all three sites rose steadily during the study period. In Kisumu, Nairobi and Kilifi, seroprevalences (95% CI) at the beginning of the study were 36.0% (28.2-44.4%), 32.4% (23.1-42.4%), and 14.5% (9.1-21%), and respectively; at the end they were 42.0% (34.7-50.0%), 50.2% (39.7-61.1%), and 24.7% (17.5-32.6%), respectively. Seroprevalence was substantially lower among children (ConclusionBy May 2021 in three broadly representative populations of unvaccinated individuals in Kenya, seroprevalence of anti-SARS-CoV-2 IgG was 25-50%. There was wide variation in cumulative incidence by location and age.