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Symptom prevalence and Secondary Attack Rate of SARS-CoV-2 in Rural Kenyan Households: a prospective cohort study
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  • Katherine Gallagher,
  • Joyce Nyiro,
  • Charles Agoti,
  • James Nyagwange,
  • Angela Karani,
  • Christian Bottomley,
  • Nickson Murunga,
  • George Githinji,
  • Martin Mutunga,
  • Lynette Ochola-Oyier,
  • Ivy Kombe,
  • Amek Nyaguara,
  • E Wangeci Kagucia,
  • George Warimwe,
  • Ambrose Agweyu,
  • Benjamin Tsofa,
  • Philip Bejon,
  • J Scott,
  • David Nokes
Katherine Gallagher
London School of Hygiene and Tropical Medicine Faculty of Epidemiology and Population Health

Corresponding Author:katherine.gallagher@lshtm.ac.uk

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Joyce Nyiro
Kenya Medical Research Institute (KEMRI) - Wellcome Trust Research Programme
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Charles Agoti
Kenya Medical Research Institute (KEMRI) - Wellcome Trust Research Programme
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James Nyagwange
KEMRI-Wellcome Trust Research Programme
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Angela Karani
KEMRI-Wellcome Trust Research Programme
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Christian Bottomley
London School of Hygiene and Tropical Medicine Faculty of Epidemiology and Population Health
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Nickson Murunga
KEMRI-Wellcome Trust Research Programme
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George Githinji
KEMRI-Wellcome Trust Research Programme
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Martin Mutunga
KEMRI-Wellcome Trust Research Programme
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Lynette Ochola-Oyier
KEMRI-Wellcome Trust Research Programme
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Ivy Kombe
KEMRI-Wellcome Trust Research Programme
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Amek Nyaguara
KEMRI-Wellcome Trust Research Programme
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E Wangeci Kagucia
KEMRI-Wellcome Trust Research Programme
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George Warimwe
KEMRI-Wellcome Trust Research Programme
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Ambrose Agweyu
KEMRI-Wellcome Trust Research Programme
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Benjamin Tsofa
KEMRI-Wellcome Trust Research Programme
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Philip Bejon
KEMRI-Wellcome Trust Research Programme
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J Scott
KEMRI-Wellcome Trust Research Programme
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David Nokes
KEMRI
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Abstract

Background We estimated the secondary attack rate of SARS-CoV-2 among household contacts of PCR-confirmed cases of COVID-19 in rural Kenya and analysed risk factors for transmission. Methods We enrolled incident PCR-confirmed cases and their household members. At baseline, a questionnaire, a blood sample, and naso-oropharyngeal swabs were collected. Household members were followed 4, 7, 10, 14, 21 and 28 days after the date of the first PCR-positive in the household; naso-oropharyngeal swabs were collected at each visit and used to define secondary cases. Blood samples were collected every 1-2 weeks. Symptoms were collected in a daily symptom diary. We used binomial regression to estimate secondary attack rates and survival analysis to analyze risk factors for transmission. Results A total of 119 households with at least one positive household member were enrolled between October 2020 and September 2022, comprising 503 household members; 226 remained in follow up at day-14 (45%). A total of 43 secondary cases arose within 14 days of identification of the primary case, 81 household members remained negative. The 7-day secondary attack rate was 4% (95%CI 1-10%), the 14-day secondary attack rate was 28% (95%CI 17-40%). Of 38 secondary cases with data, 8 reported symptoms (21%, 95%CI 8-34%). Antibody to SARS-CoV-2 spike protein at enrolment was not associated with risk of becoming a secondary case. Conclusion Households in our setting experienced a lower 7-day attack rate than a recent meta-analysis indicated as the global average (23-43% depending on variant), and infection is mostly asymptomatic in our setting.
04 Apr 2023Submitted to Influenza and other respiratory viruses
05 Apr 2023Submission Checks Completed
05 Apr 2023Assigned to Editor
10 Apr 2023Reviewer(s) Assigned
23 Jun 2023Review(s) Completed, Editorial Evaluation Pending
28 Jun 2023Editorial Decision: Revise Minor
22 Jul 20231st Revision Received
27 Jul 2023Submission Checks Completed
27 Jul 2023Assigned to Editor
27 Jul 2023Review(s) Completed, Editorial Evaluation Pending
07 Aug 2023Editorial Decision: Accept