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Otiende M, Nyaguara A, Bottomley C, Walumbe D, Mochamah G, Amadi D, Nyundo C, Kagucia EW, Etyang AO, Adetifa IMO, Brand SPC, Maitha E, Chondo E, Nzomo E, Aman R, Mwangangi M, Amoth P, Kasera K, Ng'ang'a W, Barasa E, Tsofa B, Mwangangi J, Bejon P, Agweyu A, Williams TN, Scott JAG. Impact of COVID-19 on mortality in coastal Kenya: a longitudinal open cohort study. Nat Commun 2023; 14:6879. [PMID: 37898630 PMCID: PMC10613220 DOI: 10.1038/s41467-023-42615-6] [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] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Accepted: 10/17/2023] [Indexed: 10/30/2023] Open
Abstract
The mortality impact of COVID-19 in Africa remains controversial because most countries lack vital registration. We analysed excess mortality in Kilifi Health and Demographic Surveillance System, Kenya, using 9 years of baseline data. SARS-CoV-2 seroprevalence studies suggest most adults here were infected before May 2022. During 5 waves of COVID-19 (April 2020-May 2022) an overall excess mortality of 4.8% (95% PI 1.2%, 9.4%) concealed a significant excess (11.6%, 95% PI 5.9%, 18.9%) among older adults ( ≥ 65 years) and a deficit among children aged 1-14 years (-7.7%, 95% PI -20.9%, 6.9%). The excess mortality rate for January 2020-December 2021, age-standardised to the Kenyan population, was 27.4/100,000 person-years (95% CI 23.2-31.6). In Coastal Kenya, excess mortality during the pandemic was substantially lower than in most high-income countries but the significant excess mortality in older adults emphasizes the value of achieving high vaccine coverage in this risk group.
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Affiliation(s)
- M Otiende
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya.
| | - A Nyaguara
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - C Bottomley
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, Keppel Street London, London, WC1E 7HT, UK
| | - D Walumbe
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - G Mochamah
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - D Amadi
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - C Nyundo
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - E W Kagucia
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - A O Etyang
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - I M O Adetifa
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, Keppel Street London, London, WC1E 7HT, UK
| | - S P C Brand
- The Zeeman Institute for Systems Biology and Infectious Disease Epidemiology Research, University of Warwick, Coventry, CV4 7AL, UK
| | - E Maitha
- Department of Health, Kilifi County, Kilifi, Kenya
| | - E Chondo
- Department of Health, Kilifi County, Kilifi, Kenya
| | - E Nzomo
- Kilifi County Hospital, Kilifi, Kenya
| | - R Aman
- Ministry of Health, Government of Kenya; Afya House, Cathedral Road, Nairobi, Kenya
| | - M Mwangangi
- Ministry of Health, Government of Kenya; Afya House, Cathedral Road, Nairobi, Kenya
| | - P Amoth
- Ministry of Health, Government of Kenya; Afya House, Cathedral Road, Nairobi, Kenya
| | - K Kasera
- Ministry of Health, Government of Kenya; Afya House, Cathedral Road, Nairobi, Kenya
| | - W Ng'ang'a
- Presidential Policy and Strategy Unit, The Presidency, Government of Kenya, Nairobi, Kenya
| | - E Barasa
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - B Tsofa
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - J Mwangangi
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - P Bejon
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Nuffield Department of Clinical Medicine, University of Oxford, Old Road Campus, Oxford, OX3 7BN, UK
| | - A Agweyu
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
| | - T N Williams
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Institute for Global Health Innovation, Imperial College, London, SW72AS, UK
| | - J A G Scott
- KEMRI-Wellcome Research Trust Programme, PO Box 230, Kilifi, 80108, Kenya
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, Keppel Street London, London, WC1E 7HT, UK
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Bottomley C, Otiende M, Uyoga S, Gallagher K, Kagucia EW, Etyang AO, Mugo D, Gitonga J, Karanja H, Nyagwange J, Adetifa IMO, Agweyu A, Nokes DJ, Warimwe GM, Scott JAG. Quantifying previous SARS-CoV-2 infection through mixture modelling of antibody levels. Nat Commun 2021; 12:6196. [PMID: 34702829 PMCID: PMC8548402 DOI: 10.1038/s41467-021-26452-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 09/17/2021] [Indexed: 11/09/2022] Open
Abstract
As countries decide on vaccination strategies and how to ease movement restrictions, estimating the proportion of the population previously infected with SARS-CoV-2 is important for predicting the future burden of COVID-19. This proportion is usually estimated from serosurvey data in two steps: first the proportion above a threshold antibody level is calculated, then the crude estimate is adjusted using external estimates of sensitivity and specificity. A drawback of this approach is that the PCR-confirmed cases used to estimate the sensitivity of the threshold may not be representative of cases in the wider population-e.g., they may be more recently infected and more severely symptomatic. Mixture modelling offers an alternative approach that does not require external data from PCR-confirmed cases. Here we illustrate the bias in the standard threshold-based approach by comparing both approaches using data from several Kenyan serosurveys. We show that the mixture model analysis produces estimates of previous infection that are often substantially higher than the standard threshold analysis.
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Affiliation(s)
- C Bottomley
- International Statistics and Epidemiology Group, London School of Hygiene & Tropical Medicine, London, UK.
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK.
| | - M Otiende
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - S Uyoga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - K Gallagher
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - E W Kagucia
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - A O Etyang
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - D Mugo
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - J Gitonga
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - H Karanja
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - J Nyagwange
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - I M O Adetifa
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
| | - A Agweyu
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Oxford University, Oxford, UK
| | - D J Nokes
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- School of Life Sciences, University of Warwick, Coventry, UK
| | - G M Warimwe
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Oxford University, Oxford, UK
| | - J A G Scott
- Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, UK
- KEMRI-Wellcome Trust Research Programme, Kilifi, Kenya
- Nuffield Department of Medicine, Oxford University, Oxford, UK
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Githang'a D, Wangia RN, Mureithi MW, Wandiga SO, Mutegi C, Ogutu B, Agweyu A, Wang JS, Anzala O. The effects of aflatoxin exposure on Hepatitis B-vaccine induced immunity in Kenyan children. Curr Probl Pediatr Adolesc Health Care 2019; 49:117-130. [PMID: 31103452 PMCID: PMC7116700 DOI: 10.1016/j.cppeds.2019.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
BACKGROUND Globally, approximately three million children die each year from vaccine preventable infectious diseases mainly in developing countries. Despite the success of the expanded immunization program, not all infants and children around the world develop the same protective immune response to the same vaccine. A vaccine must induce a response over the basal immune response that may be driven by population-specific, environmental or socio-economic factors. Mycotoxins like aflatoxins are immune suppressants that are confirmed to interfere with both cell-mediated and acquired immunity. The mechanism of aflatoxin toxicity is through the binding of the bio-activated AFB1-8, 9-epoxide to cellular macromolecules. METHODS We studied Hepatitis B surface antibodies [anti-HBs] levels to explore the immune modulation effects of dietary exposure to aflatoxins in children aged between one and fourteen years in Kenya. Hepatitis B vaccine was introduced for routine administration for Kenyan infants in November 2001. To assess the effects of aflatoxin on immunogenicity of childhood vaccines Aflatoxin B1-lysine in blood serum samples were determined using High Performance Liquid Chromatography with Fluorescence detection while anti-HBs were measured using Bio-ELISA anti-HBs kit. RESULTS The mean ± SD of AFB1-lysine adducts in our study population was 45.38 ± 87.03 pg/mg of albumin while the geometric mean was 20.40 pg/mg. The distribution of AFB1-lysine adducts was skewed to the right. Only 98/205 (47.8%) of the study population tested positive for Hepatitis B surface antibodies. From regression analysis, we noted that for every unit rise in serum aflatoxin level, anti-HBs dropped by 0.91 mIU/ml (-0.9110038; 95% C.I -1.604948, -0.21706). CONCLUSION Despite high coverage of routine immunization, less than half of the study population had developed immunity to HepB. Exposure to aflatoxin was high and weakly associated with low anti-HBs antibodies. These findings highlight a potentially significant role for environmental factors that may contribute to vaccine effectiveness warranting further research.
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Affiliation(s)
- D Githang'a
- KAVI - Institute of Clinical Research, University of Nairobi, Kenya; Department of Medical Microbiology, School of Medicine, College of Health Sciences, University of Nairobi, Kenya.
| | - R N Wangia
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, United States
| | - M W Mureithi
- KAVI - Institute of Clinical Research, University of Nairobi, Kenya; Department of Medical Microbiology, School of Medicine, College of Health Sciences, University of Nairobi, Kenya
| | - S O Wandiga
- Department of Chemistry, College of Biological and Physical Sciences, University of Nairobi, Kenya
| | - C Mutegi
- International Institute of Tropical Agriculture [IITA], P.O BOX 30772-00100, Nigeria
| | - B Ogutu
- Centre for Clinical Research-Kenya Medical Research Institute, Kenya
| | - A Agweyu
- KEMRI-Wellcome Trust Research Programme, P.O. Box 43640 - 00100, Nairobi, Kenya
| | - J-S Wang
- Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, GA 30602, United States
| | - O Anzala
- KAVI - Institute of Clinical Research, University of Nairobi, Kenya; Department of Medical Microbiology, School of Medicine, College of Health Sciences, University of Nairobi, Kenya
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