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

Cheikh Talla (1) , Cheikh Loucoubar (1) , Jerlie Loko Roka (2) , Mamadou A. Barry (1) , Seynabou Ndiaye (1) , Maryam Diarra (1) , Oumar Faye (3) , Moussa Dia (3) , Mamadou Diop (1) , Oumar Ndiaye (3) , Adama Tall (1) , Rokhaya Faye (4) , Adji Astou Mbow (4) , Babacar Diouf (4) , Jean Pierre Diallo (5) , Mamadou Ndiaye (5) , Tom Woudenberg (6) , Michael White (6) , Jim Ting (2) , Cheikh Tidiane Diagne (3) , Omer Pasi (2) , Boly Diop (5) , Amadou A. Sall (3) , Inès Vigan‑womas (4) , Ousmane Faye (3)

1 Pôle Epidémiologie, Recherche clinique et Science des données [Dakar, Sénégal]
2 CDC - Centers for Disease Control and Prevention [Atlanta]
3 Département de virologie - Virology Department [Dakar]
4 Pôle Immunophysiopathologie et Maladies Infectieuses
5 MSAS - Ministère de la Santé et de l'Action sociale (Sénégal)
6 Malaria : parasites et hôtes - Malaria : parasites and hosts

Background: Senegal reported the first COVID-19 case on March 2, 2020. A nationwide cross-sectional epidemiological survey was conducted to capture the true extent of COVID-19 exposure. Methods: Multi-stage random cluster sampling of households was carried out between October 24 and November 26, 2020, at the end of the first wave of COVID-19 transmission. Anti-SARS-CoV-2 antibodies (IgG and/or IgM) were screened using three distinct ELISA assays. Adjusted prevalence for the survey design were calculated for each test separately, and thereafter combined. Crude, adjusted prevalence based on tests performances and weighted prevalence by sex-age strata were estimated to assess the seroprevalence. Findings: Of the 1,463 participants included in this study, 58·8% were women and the mean age of participants was 29·2 years (range 0·25–82·0). The national seroprevalence was estimated at 28 . 4% (95% CI: 26·1-30·8). There was substantial regional variability. Four regions recorded the highest seroprevalence: Ziguinchor (56·7%), Sedhiou (48·0%), Dakar (44·0%) and Kaolack (32·7%) whereas, Louga (11·1%) and Matam (11·2%), located in the Center-North, were less impacted in our analysis. All age groups were impacted and the prevalence of SARS-CoV-2 was comparable in symptomatic and asymptomatic groups. We estimated 4,744,392 SARS-CoV-2 (95% CI: 4,360,164 – 5,145,327) potential infected in Senegal compared to 16,089 COVID-19 RT-PCR laboratory-confirmed cases reported at the time of the survey. Interpretation: These results provide an estimate of SARS-CoV-2 virus dissemination in the Senegalese population. Preventive and control measures need to be reinforced in the country and especially in the south border regions.

Mots clés: SARS-CoV-2; Serology; ELISA; IgG and IgM; seroprevalence; population-based survey; Senegal

Domaines: Microbiologie et Parasitologie; Immunologie; Biologie cellulaire; Biologie moléculaire; Santé publique et épidémiologie

Cheikh Talla, Cheikh Loucoubar, Jerlie Loko Roka, Mamadou A. Barry, Seynabou Ndiaye, et al.. Seroprevalence of anti-SARS-CoV-2 antibodies in Senegal: a national population-based cross-sectional survey, between October and November 2020. 2022. ⟨pasteur-03752584v1⟩