Seroprevalence of SARS-CoV-2 antibodies in the poorest region of Brazil: results from a population-based study

Abstract

Population-based seroprevalence studies on coronavirus disease 2019 (COVID-19) in lowand middle-income countries are lacking. We investigated the seroprevalence of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) antibodies in Sergipe state, Northeast Brazil, using rapid IgM.IgG antibody test and fluorescence immunoassay. The seroprevalence was 9.3% (95% CI 8.5.10.1), 10.2% (95% CI 9.2.11.3) for women and 7.9% (IC 95% 6.8.9.1) for men (P = 0.004). We found a decline in the prevalence of SARS-CoV- 2 antibodies according to age, but the differences were not statistically significant: 0.19 years (9.9%; 95% CI 7.8.12.5), 20.59 years (9.3%; 95% CI 8.4.10.3) and ≥60 years (9.0%; 95% CI 7.5.10.8) (P = 0.517). The metropolitan area had a higher seroprevalence (11.7%, 95% CI 10.3.13.2) than outside municipalities (8.0%, 95% CI 7.2.8.9) (P<0.001). These findings highlight the importance of serosurveillance to estimate the real impact of the COVID-19 outbreak and thereby provide data to better understand the spread of the virus, as well as providing information to guide stay-at-home measures and other policies. In addition, these results may be useful as basic data to follow the progress of COVID-19 outbreak as social restriction initiatives start to be relaxed in Brazil.