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Kagucia EW, Ziraba AK, Nyagwange J, Kutima B, Kimani M, Akech D, Ng'oda M, Sigilai A, Mugo D, Karanja H, Gitonga J, Karani A, Toroitich M, Karia B, Otiende M, Njeri A, Aman R, Amoth P, Mwangangi M, Kasera K, Ng'ang'a W, Voller S, Ochola‐Oyier LI, Bottomley C, Nyaguara A, Munywoki PK, Bigogo G, Maitha E, Uyoga S, Gallagher KE, Etyang AO, Barasa E, Mwangangi J, Bejon P, Adetifa IMO, Warimwe GM, Scott JAG, Agweyu A. SARS-CoV-2 seroprevalence and implications for population immunity: Evidence from two Health and Demographic Surveillance System sites in Kenya, February-December 2022. Influenza Other Respir Viruses 2023; 17:e13173. [PMID: 37752065 PMCID: PMC10522478 DOI: 10.1111/irv.13173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 06/19/2023] [Accepted: 06/28/2023] [Indexed: 09/28/2023] Open
Abstract
BACKGROUND We sought to estimate SARS-CoV-2 antibody seroprevalence within representative samples of the Kenyan population during the third year of the COVID-19 pandemic and the second year of COVID-19 vaccine use. METHODS We conducted cross-sectional serosurveys among randomly selected, age-stratified samples of Health and Demographic Surveillance System (HDSS) residents in Kilifi and Nairobi. Anti-spike (anti-S) immunoglobulin G (IgG) serostatus was measured using a validated in-house ELISA and antibody concentrations estimated with reference to the WHO International Standard for anti-SARS-CoV-2 immunoglobulin. RESULTS HDSS residents were sampled in February-June 2022 (Kilifi HDSS N = 852; Nairobi Urban HDSS N = 851) and in August-December 2022 (N = 850 for both sites). Population-weighted coverage for ≥1 doses of COVID-19 vaccine were 11.1% (9.1-13.2%) among Kilifi HDSS residents by November 2022 and 34.2% (30.7-37.6%) among Nairobi Urban HDSS residents by December 2022. Population-weighted anti-S IgG seroprevalence among Kilifi HDSS residents increased from 69.1% (65.8-72.3%) by May 2022 to 77.4% (74.4-80.2%) by November 2022. Within the Nairobi Urban HDSS, seroprevalence by June 2022 was 88.5% (86.1-90.6%), comparable with seroprevalence by December 2022 (92.2%; 90.2-93.9%). For both surveys, seroprevalence was significantly lower among Kilifi HDSS residents than among Nairobi Urban HDSS residents, as were antibody concentrations (p < 0.001). CONCLUSION More than 70% of Kilifi residents and 90% of Nairobi residents were seropositive for anti-S IgG by the end of 2022. There is a potential immunity gap in rural Kenya; implementation of interventions to improve COVID-19 vaccine uptake among sub-groups at increased risk of severe COVID-19 in rural settings is recommended.
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Affiliation(s)
| | | | | | | | | | - Donald Akech
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | - Maurine Ng'oda
- African Population and Health Research CenterNairobiKenya
| | | | - Daisy Mugo
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | | | - John Gitonga
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | | | | | | | - Mark Otiende
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | - Anne Njeri
- African Population and Health Research CenterNairobiKenya
| | | | | | | | | | - Wangari Ng'ang'a
- Presidential Policy and Strategy UnitThe Presidency, Government of KenyaNairobiKenya
| | - Shirine Voller
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- London School of Hygiene and Tropical MedicineLondonUK
| | | | | | | | - Patrick K. Munywoki
- Division for Global Health ProtectionUS Centers of Disease Control and Prevention, Center for Global HealthNairobiKenya
| | | | | | - Sophie Uyoga
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
| | - Katherine E. Gallagher
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- London School of Hygiene and Tropical MedicineLondonUK
| | | | | | | | - Philip Bejon
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of MedicineOxford UniversityOxfordUK
| | - Ifedayo M. O. Adetifa
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- London School of Hygiene and Tropical MedicineLondonUK
| | - George M. Warimwe
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of MedicineOxford UniversityOxfordUK
| | - J. Anthony G. Scott
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- London School of Hygiene and Tropical MedicineLondonUK
| | - Ambrose Agweyu
- KEMRI‐Wellcome Trust Research ProgrammeKilifiKenya
- London School of Hygiene and Tropical MedicineLondonUK
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Etyang AO, Adetifa I, Omore R, Misore T, Ziraba AK, Ng’oda MA, Gitau E, Gitonga J, Mugo D, Kutima B, Karanja H, Toroitich M, Nyagwange J, Tuju J, Wanjiku P, Aman R, Amoth P, Mwangangi M, Kasera K, Ng’ang’a W, Akech D, Sigilai A, Karia B, Karani A, Voller S, Agoti CN, Ochola-Oyier LI, Otiende M, Bottomley C, Nyaguara A, Uyoga S, Gallagher K, Kagucia EW, Onyango D, Tsofa B, Mwangangi J, Maitha E, Barasa E, Bejon P, Warimwe GM, Scott JAG, Agweyu A. SARS-CoV-2 seroprevalence in three Kenyan health and demographic surveillance sites, December 2020-May 2021. PLOS Glob Public Health 2022; 2:e0000883. [PMID: 36962821 PMCID: PMC10021917 DOI: 10.1371/journal.pgph.0000883] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Accepted: 07/12/2022] [Indexed: 11/19/2022]
Abstract
BACKGROUND Most 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. METHODS We 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. RESULTS We 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 (<16 years) than among adults at all three sites (p≤0.001). CONCLUSION By 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.
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Affiliation(s)
| | - Ifedayo Adetifa
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | - Richard Omore
- Kenya Medical Research Institute Centre for Global Health Research, Kisumu, Kenya
| | - Thomas Misore
- Kenya Medical Research Institute Centre for Global Health Research, Kisumu, Kenya
| | | | | | - Evelyn Gitau
- African Population and Health Research Center, Nairobi, Kenya
| | - John Gitonga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Daisy Mugo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Henry Karanja
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - James Tuju
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | - Wangari Ng’ang’a
- Presidential Policy and Strategy Unit, The Presidency, Government of Kenya, Nairobi, Kenya
| | - Donald Akech
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | - Angela Karani
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Shirine Voller
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | | | - Mark Otiende
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | - Amek Nyaguara
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - Sophie Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | | | | | | | | | | | | | - Edwine Barasa
- Health Economics Research Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, United Kingdom
| | - Philip Bejon
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, United Kingdom
| | - George M. Warimwe
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, Oxford University, Oxford, United Kingdom
| | - J. Anthony G. Scott
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- London School of Hygiene and Tropical Medicine, London, United Kingdom
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