SARS-CoV-2 in Ivory Coast: serosurveillance survey among mines workers

Background: Eight months after the detection of the first COVID-19 case in Africa, 1,262,476 cases have been reported in African countries compared to 72 million worldwide. The real burden of SARS-CoV-2 infection in West Africa is not clearly defined. The aim of the study was to evaluate the seroprevalence of SARS-CoV-2 in half of the 3,380 workers of several mining companies operating in two mines in the Ivory Coast and having its headquarters in the economic capital Abidjan. Methods: From 15th July to 13th October 2020, a voluntary serological test campaign was performed in the 3 sites where the companies operate: two mines, and the headquarters in Abidjan.We performed a COVID-PRESTO rapid test for the detection of IgG and IgM on capillary blood. A multivariate analysis was performed to identify independent sociodemographic characteristics associated with a higher SARS-CoV-2 seroprevalence rate. Results: A total of 1,687 subjects were tested. 91% were male (n= 1,536) and mean age was 37 years old. The overall crude seroprevalence rate was 25.1% (n=422), but differing significantly between different sites, rising from 13.6% (11.2%-16.1%) in mine A to 34.4% (31.1%-37.7%) in mine B and 34.7% (26.2%-43.2%) in Abidjan. Non-resident workers in mines had a significantly lower prevalence rate than those living full-time in mines. Seroprevalence was 26.5% in natives of the Ivory Coast, while people coming from countries other than Africa were less likely to be SARS-CoV-2 seropositive. Among the 422 positive subjects, 74 reported mild symptoms in the three previous months and one was hospitalized for a severe COVID-19 infection. Conclusion: The prevalence of SARS-CoV-2 infection among mine workers in Ivory Coast is high. The low morbidity observed has probably led to an underestimation of the burden of this infection in West Africa. The high prevalence reported in subjects living in Abidjan, who have not any close contact with mine workers, may be indicative of the real seroprevalence in the Ivory Coast capital.