Seroprevalence of anti-SARS-CoV-2 antibodies in Senegal: a national population-based cross-sectional survey, between October and November 2020

Cheikh Talla; Cheikh Loucoubar; Jerlie Loko Roka; Mamadou A Barry; Seynabou Ndiaye; Maryam Diarra; Mareme Seye Thiam; Oumar Faye; Moussa Dia; Mamadou Diop; Oumar Ndiaye; Adama Tall; Rokhaya Faye; Adji Astou Mbow; Babacar Diouf; Jean Pierre Diallo; Ibrahima Mamby Keita; Mamadou Ndiaye; Tom Woudenberg; Michael White; Jim Ting; Cheikh Tidiane Diagne; Omer Pasi; Boly Diop; Amadou A Sall; Inès Vigan-Womas; Ousmane Faye

doi:10.1016/j.ijregi.2022.02.007

Seroprevalence of anti-SARS-CoV-2 antibodies in Senegal: a national population-based cross-sectional survey, between October and November 2020

IJID Reg. 2022 Jun:3:117-125. doi: 10.1016/j.ijregi.2022.02.007. Epub 2022 Mar 5.

Authors

Cheikh Talla¹, Cheikh Loucoubar¹, Jerlie Loko Roka², Mamadou A Barry¹, Seynabou Ndiaye¹, Maryam Diarra¹, Mareme Seye Thiam¹, Oumar Faye³, Moussa Dia³, Mamadou Diop¹, Oumar Ndiaye³, Adama Tall¹, Rokhaya Faye⁴, Adji Astou Mbow⁴, Babacar Diouf⁴, Jean Pierre Diallo⁵, Ibrahima Mamby Keita⁵, Mamadou Ndiaye⁵, Tom Woudenberg⁶, Michael White⁶, Jim Ting², Cheikh Tidiane Diagne³, Omer Pasi², Boly Diop⁵, Amadou A Sall³, Inès Vigan-Womas⁴, Ousmane Faye³

Affiliations

¹ Epidemiology, Clinical Research and Data Sciences Department, Institut Pasteur de Dakar, Dakar, Senegal.
² Centers for Disease Control and Prevention (CDC), Atlanta, Georgia, USA.
³ Virology Department, Institut Pasteur de Dakar, Dakar, Senegal.
⁴ Immunophysiopathology and Infectious Diseases Department, Institut Pasteur de Dakar, Dakar, Senegal.
⁵ Prevention Department, Surveillance Division, Ministry of Health and Social Action, Dakar, Senegal.
⁶ Malaria: Parasites and Hosts Unit, Department of Parasites and Insect Vectors, Institut Pasteur, Paris, France.

Abstract

Objectives: A nationwide cross-sectional epidemiological survey was conducted to capture the true extent of coronavirus disease 2019 (COVID-19) exposure in Senegal.

Methods: Multi-stage random cluster sampling of households was performed between October and November 2020, at the end of the first wave of COVID-19 transmission. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies were screened using three distinct ELISA assays. Adjusted prevalence rates for the survey design were calculated for each test separately, and thereafter combined. Crude and adjusted prevalence rates based on test performance were estimated to assess the seroprevalence. As some samples were collected in high malaria endemic areas, the relationship between SARS-CoV-2 seroreactivity and antimalarial humoral immunity was also investigated.

Results: Of the 1463 participants included in this study, 58.8% were female and 41.2% were male; their mean age was 29.2 years (range 0.20-84.8.0 years). The national seroprevalence was estimated at 28.4% (95% confidence interval 26.1-30.8%). There was substantial regional variability. All age groups were impacted, and the prevalence of SARS-CoV-2 was comparable in the symptomatic and asymptomatic groups. An estimated 4 744 392 (95% confidence interval 4 360 164-5 145 327) were potentially infected with SARS-CoV-2 in Senegal, while 16 089 COVID-19 RT-PCR laboratory-confirmed cases were reported by the national surveillance. No correlation was found between SARS-CoV-2 and Plasmodium seroreactivity.

Conclusions: These results provide a better estimate of SARS-CoV-2 dissemination in the Senegalese population. Preventive and control measures need to be reinforced in the country and especially in the south border regions.

Keywords: ELISA; IgG and IgM; Population-based survey; SARS-CoV-2; Senegal; Serology; Seroprevalence.