SARS-COV-2 Seroprevalence and associated factors among people living in different provinces in Chad

Background : Chad with 7,698 confirmed cases of infection and 194 deaths since the beginning of COVID-19 pandemics one of the African countries with the lowest reported cases[i]. However, this figure probably underestimates the actual spread of the virus, due to the low rate of diagnosis. High rate of asymptomatic infections reflects reality of SARS-CoV-2 infection in Chad. In this study, we estimated the seroprevalence and factors associated with SARS-CoV-2 infection. Methods: A total of 1,290 samples were taken between September and December 2022 in 10 provinces of Chad. IgG antibodies to the nucleocapsid (N) protein of SARS-CoV-2 were identified by ELISA method. Results: The overall seroprevalence was 83.0% [95% CI = 81.6% t- 85.5%], with variations between provinces, ranging from 99.22% [95% CI = 94% - 100%] in Moundou (Southern Chad) to 46.80% [95% CI = 36% -57%] in Biltine (Eastern Chad). Factors associated with the seroprevalence of SARS-CoV-2 were: military occupation (OR= 0.37 CI [0.80-1.77] p=0.025) and group blood (OR= 0.16 CI [0.02-1.06] p=0.058). Other factors, such as gender age, were not statistically associated with seroprevalence. Conclusion Our results indicates that the seroprevalence of COVID-19 in Chad ranks among the highest in Africa. These estimates could guide the response and public health policy decisions. This could enhance the handling of upcoming outbreaks involving respiratory pathogens.