Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2022 Oct 14;17(10):e0265478.
doi: 10.1371/journal.pone.0265478. eCollection 2022.

Sero-surveillance for IgG to SARS-CoV-2 at antenatal care clinics in three Kenyan referral hospitals: Repeated cross-sectional surveys 2020-21

Ruth K Lucinde  1 , Daisy Mugo  1 , Christian Bottomley  2 , Angela Karani  1 , Elizabeth Gardiner  1 , Rabia Aziza  3 , John N Gitonga  1 , Henry Karanja  1 , James Nyagwange  1 , James Tuju  1 , Perpetual Wanjiku  1 , Edward Nzomo  4 , Evans Kamuri  5 , Kaugiria Thuranira  5 , Sarah Agunda  5 , Gideon Nyutu  1 , Anthony O Etyang  1 , Ifedayo M O Adetifa  1   2 , Eunice Kagucia  1 , Sophie Uyoga  1 , Mark Otiende  1 , Edward Otieno  1 , Leonard Ndwiga  1 , Charles N Agoti  1 , Rashid A Aman  6 , Mercy Mwangangi  6 , Patrick Amoth  6 , Kadondi Kasera  6 , Amek Nyaguara  1 , Wangari Ng'ang'a  7 , Lucy B Ochola  8 , Emukule Namdala  9 , Oscar Gaunya  9 , Rosemary Okuku  9 , Edwine Barasa  1   10 , Philip Bejon  1   10 , Benjamin Tsofa  1 , L Isabella Ochola-Oyier  1 , George M Warimwe  1   10 , Ambrose Agweyu  1 , J Anthony G Scott  1   2   10 , Katherine E Gallagher  1   2
Affiliations

Sero-surveillance for IgG to SARS-CoV-2 at antenatal care clinics in three Kenyan referral hospitals: Repeated cross-sectional surveys 2020-21

Ruth K Lucinde et al. PLoS One. .

Abstract

Introduction: The high proportion of SARS-CoV-2 infections that have remained undetected presents a challenge to tracking the progress of the pandemic and estimating the extent of population immunity.

Methods: We used residual blood samples from women attending antenatal care services at three hospitals in Kenya between August 2020 and October 2021and a validated IgG ELISA for SARS-Cov-2 spike protein and adjusted the results for assay sensitivity and specificity. We fitted a two-component mixture model as an alternative to the threshold analysis to estimate of the proportion of individuals with past SARS-CoV-2 infection.

Results: We estimated seroprevalence in 2,981 women; 706 in Nairobi, 567 in Busia and 1,708 in Kilifi. By October 2021, 13% of participants were vaccinated (at least one dose) in Nairobi, 2% in Busia. Adjusted seroprevalence rose in all sites; from 50% (95%CI 42-58) in August 2020, to 85% (95%CI 78-92) in October 2021 in Nairobi; from 31% (95%CI 25-37) in May 2021 to 71% (95%CI 64-77) in October 2021 in Busia; and from 1% (95% CI 0-3) in September 2020 to 63% (95% CI 56-69) in October 2021 in Kilifi. Mixture modelling, suggests adjusted cross-sectional prevalence estimates are underestimates; seroprevalence in October 2021 could be 74% in Busia and 72% in Kilifi.

Conclusions: There has been substantial, unobserved transmission of SARS-CoV-2 in Nairobi, Busia and Kilifi Counties. Due to the length of time since the beginning of the pandemic, repeated cross-sectional surveys are now difficult to interpret without the use of models to account for antibody waning.

PubMed Disclaimer

Conflict of interest statement

This project was funded by a commercial source, the Wellcome Trust (grants 220991/Z/20/Z and 203077/Z/16/Z). This does not alter our adherence to PLOS ONE policies on sharing data and materials. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Authors declare no other competing interests.

Figures

Fig 1
Fig 1. Mixture distributions fitted to anti-spike IgG antibody data collected in Kilifi (KCH), Busia and Nairobi (KNH).
The red distribution represents predicted responses in individuals previously infected with SARS-CoV-2 and the blue distribution represents predicted responses in previously uninfected individuals.
Fig 2
Fig 2. Adjusted and modelled estimates of the cumulative incidence of SARS-CoV-2 infection.
Estimates are shown with 95% credible intervals.
See this image and copyright information in PMC

References

    1. World Health Organization. COVID-19 vaccines https://www.who.int/emergencies/diseases/novel-coronavirus-2019/covid-19... [Accessed 08 Dec 2021] 2021.
    1. World Health Organization. Africa faces 470 million COVID-19 vaccine shortfall in 2021. 16 September 2021 https://www.afro.who.int/news/africa-faces-470-million-covid-19-vaccine-... 2021.
    1. Ministry of Health GoK. UPDATES ON COVID-19 VACCINATION EXERCISE 21 October 2021 https://www.health.go.ke/#1621663315215-d6245403-4901.
    1. Kenya National Bureau of Statistics. Population and Housing Census (www.knbs.or.ke). 2019.
    1. Seedat S, Chemaitelly H, Ayoub H, Makhoul M, Mumtaz GR, Kanaani ZA, et al.. SARS-CoV-2 infection hospitalization, severity, criticality, and fatality rates. medRxiv. 2020:2020.11.29.20240416. doi: 10.1101/2020.11.29.20240416 - DOI - PMC - PubMed

Publication types