SARS-CoV-2 infection and antibody seroprevalence in routine surveillance patients, healthcare workers and general population in Kita region, Mali: an observational study 2020-2021

Dagmar Alber, Fadima Cheick Haidara, Juho Luoma, Laura Adubra, Per Ashorn, Ulla Ashorn, Henry Badji, Elaine Cloutman-Green, Fatoumata Diallo, Rikhard Ihamuotila, Nigel Klein, Owen Martell, Uma U. Onwuchekwa, Oumar Samaké, Samba O. Sow, Awa Traore, Kevin Wilson, Camilla Ducker, Yue Mei Fan

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    Abstract

    Objective To estimate the degree of SARS-CoV-2 transmission among healthcare workers (HCWs) and general population in Kita region of Mali. Design Routine surveillance in 12 health facilities, HCWs serosurvey in five health facilities and community serosurvey in 16 villages in or near Kita town, Mali. Setting Kita region, western Mali; local health centres around the central (regional) referral health centre. Participants Patients in routine surveillance, HCWs in local health centres and community members of all ages in populations associated with study health centres. Main outcome measures Seropositivity of ELISA test detecting SARS-CoV-2-specific total antibodies and real-time RT-PCR confirmed SARS-CoV-2 infection. Results From 2392 routine surveillance samples, 68 (2.8%, 95% CI: 2.2% to 3.6%) tested positive for SARS-CoV-2 by RT-PCR. The monthly positivity rate was 0% in June-August 2020 and gradually increased to 6% by December 2020 and 6.2% by January 2021, then declined to 5.5%, 3.3%, 3.6% and 0.8% in February, March, April and May 2021, respectively. From 397 serum samples collected from 113 HCWs, 175 (44.1%, 95% CI: 39.1% to 49.1%) were positive for SARS-CoV-2 antibodies. The monthly seroprevalence was around 10% from September to November 2020 and increased to over 40% from December 2020 to May 2021. For community serosurvey in December 2020, overall seroprevalence of SARS-CoV-2 antibodies was 27.7%. The highest age-stratified seroprevalence was observed in participants aged 60-69 years (45.5%, 95% CI: 32.3% to 58.6%). The lowest was in children aged 0-9 years (14.0%, 95% CI: 7.4% to 20.6%). Conclusions SARS-CoV-2 in rural Mali is much more widespread than assumed by national testing data and particularly in the older population and frontline HCWs. The observation is contrary to the widely expressed view, based on limited data, that COVID-19 infection rates were lower in 2020-2021 in West Africa than in other settings.

    Original languageEnglish
    Article numbere060367
    JournalBmj Open
    Volume12
    Issue number6
    DOIs
    Publication statusPublished - 16 Jun 2022
    Publication typeA1 Journal article-refereed

    Keywords

    • COVID-19
    • epidemiology
    • respiratory infections

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • General Medicine

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