Seroprevalence and risk factors of SARS-CoV-2 infection in an urban informal settlement in Nairobi, Kenya, December 2020 [version 2; peer review: 2 approved]
Terrence Q Lo,
Elizabeth Hunsperger,
Amy Herman-Roloff,
Eric Osoro,
M Kariuki Njenga,
Godfrey Bigogo,
Peninah Munyua,
Cynthia Ombok,
Ruth Njoroge,
Gilbert Kikwai,
Dennis Odhiambo,,
Patrick K Munywoki,
Caroline Nasimiyu,
Moshe Dayan Alando,
Nancy Otieno,
Caroline A Ochieng,
Immaculate Mutisya,
Isaac Ngere,
Jeanette Dawa,
Mike Powel Osita,
Alice Ouma,
Clifford Odour,
Bonventure Juma
Affiliations
Terrence Q Lo
Center for Global Health, Division of Public Health Protection, U.S. Centers for Disease Control and Prevention, Nairobi, USA
Elizabeth Hunsperger
Center for Global Health, Division of Public Health Protection, U.S. Centers for Disease Control and Prevention, Nairobi, USA
Amy Herman-Roloff
Center for Global Health, Division of Public Health Protection, U.S. Centers for Disease Control and Prevention, Nairobi, USA
Eric Osoro
Global Health Kenya, Washington State University, Nairobi, USA
M Kariuki Njenga
Global Health Kenya, Washington State University, Nairobi, USA
Godfrey Bigogo
Centre for Global Health Research,, Kenya Medical Research Institute, Kisumu, Kenya
Peninah Munyua
Center for Global Health, Division of Public Health Protection, U.S. Centers for Disease Control and Prevention, Nairobi, USA
Cynthia Ombok
Global Health Kenya, Washington State University, Nairobi, USA
Ruth Njoroge
Global Health Kenya, Washington State University, Nairobi, USA
Gilbert Kikwai
Centre for Global Health Research, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
Dennis Odhiambo,
Centre for Global Health Research, Kenya Medical Research Institute (KEMRI), Nairobi, Kenya
Introduction: Urban informal settlements may be disproportionately affected by the COVID-19 pandemic due to overcrowding and other socioeconomic challenges that make adoption and implementation of public health mitigation measures difficult. We conducted a seroprevalence survey in the Kibera informal settlement, Nairobi, Kenya, to determine the extent of SARS-CoV-2 infection. Methods: Members of randomly selected households from an existing population-based infectious disease surveillance (PBIDS) provided blood specimens between 27th November and 5th December 2020. The specimens were tested for antibodies to the SARS-CoV-2 spike protein. Seroprevalence estimates were weighted by age and sex distribution of the PBIDS population and accounted for household clustering. Multivariable logistic regression was used to identify risk factors for individual seropositivity. Results: Consent was obtained from 523 individuals in 175 households, yielding 511 serum specimens that were tested. The overall weighted seroprevalence was 43.3% (95% CI, 37.4 – 49.5%) and did not vary by sex. Of the sampled households, 122(69.7%) had at least one seropositive individual. The individual seroprevalence increased by age from 7.6% (95% CI, 2.4 – 21.3%) among children (<5 years), 32.7% (95% CI, 22.9 – 44.4%) among children 5 – 9 years, 41.8% (95% CI, 33.0 – 51.1%) for those 10-19 years, and 54.9%(46.2 – 63.3%) for adults (≥20 years). Relative to those from medium-sized households (3 and 4 individuals), participants from large (≥5 persons) households had significantly increased odds of being seropositive, aOR, 1.98(95% CI, 1.17 – 1.58), while those from small-sized households (≤2 individuals) had increased odds but not statistically significant, aOR, 2.31 (95% CI, 0.93 – 5.74). Conclusion: In densely populated urban settings, close to half of the individuals had an infection to SARS-CoV-2 after eight months of the COVID-19 pandemic in Kenya. This highlights the importance to prioritize mitigation measures, including COVID-19 vaccine distribution, in the crowded, low socioeconomic settings.
