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
Ulla Ashorn,
Per Ashorn,
Nigel Klein,
Samba O Sow,
Camilla Ducker,
Elaine Cloutman-Green,
Dagmar Alber,
Fadima Cheick Haidara,
Juho Luoma,
Laura Adubra,
Henry Badji,
Fatoumata Diallo,
Rikhard Ihamuotila,
Owen Martell,
Uma U Onwuchekwa,
Oumar Samaké,
Awa Traore,
Kevin Wilson,
Yue-Mei Fan
Affiliations
Ulla Ashorn
13 Centre for Child Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Per Ashorn
Center for Child Health Research, Faculty of Medicine and Health Technology, University of Tampere, Tampere, Pirkanmaa, Finland
Nigel Klein
University College London, London, UK
Samba O Sow
2 Centre pour le Développement des Vaccins, Ministère de la Santé, Bamako, Mali
Camilla Ducker
Tro Da Ltd, London, UK
Elaine Cloutman-Green
Great Ormond Street Institute of Child Health, University College London, London, UK
Dagmar Alber
Great Ormond Street Institute of Child Health, University College London, London, UK
Fadima Cheick Haidara
2 Centre pour le Développement des Vaccins, Bamako, Mali
Juho Luoma
Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Laura Adubra
Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Henry Badji
Center for Vaccine Development–Mali, Bamako, Mali
Fatoumata Diallo
Center for Vaccine Development–Mali, Bamako, Mali
Rikhard Ihamuotila
Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Owen Martell
Tro Da Ltd, London, UK
Uma U Onwuchekwa
Center for Vaccine Development–Mali, Bamako, Mali
Oumar Samaké
Center for Vaccine Development–Mali, Bamako, Mali
Awa Traore
Center for Vaccine Development–Mali, Bamako, Mali
Kevin Wilson
Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
Yue-Mei Fan
Center for Child, Adolescent and Maternal Health Research, Faculty of Medicine and Health Technology, Tampere University, Tampere, Finland
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.
