To estimate the SARS-CoV-2 seroprevalence in a non-metropolitan area (Vale do Rio Pardo) in the state of Rio Grande do Sul, Brazil, and determine the association between seroprevalence and adherence to social distancing measures.
For the present population-based, cross-sectional study, data were collected in four stages from August to October 2020. SARS-CoV-2 seroprevalence was assessed using an IgG/IgM rapid test. Demographic, socioeconomic, clinical, and behavioral data were also collected, with administration of a three-question survey to determine adherence to social distancing measures with a focus on the level of social distancing practiced by participants, their routine activities, and circulation of people in the home. The association between sociodemographic data and social distancing was assessed using the chi-square test for linear trends in proportions, and the association between social distancing and seroprevalence was assessed using Poisson regression (95% confidence interval [95%CI]; P < 0.05).
Of 4 252 tested and interviewed participants, 11.8% (95%CI: 10.8; 12.8) did not adhere to social distancing measures. The prevalence of a positive rapid test was 4.7% in participants who did not practice social distancing and 1.9% in participants who adhered to social distancing measures (P < 0.05). The variables male sex, age 20 to 59 years, having completed high school, monthly family income ranging from R$ 3 136.00 to R$ 6 270.00, and living in rural areas were associated with non-adherence to social distancing (P < 0.05). Adherence to all social distancing measures provided protection against SARS-CoV-2 infection (prevalence ratio: 0.37; 95%CI: 0.19; 0.73).
The results indicate a reduction in seroprevalence with the adherence to social distancing measures.