Objective: To describe study protocol and initial results of research project COVID-Inconfidentes. Method: This paper described the methodological procedures adopted and the prevalence of the SARS-CoV-2 infection in the population. A household survey was conducted between October and December 2020, in two historic cities of Brazil's mining region. Anti-SARS-CoV-2 antibody was detected using the Wondfo® rapid test. The face-to-face interview consisted of administration of a questionnaire containing registration data, sociodemographic and economic variables, living habits, general health condition, mental health, sleep habits, and eating and nutrition. Results: We evaluated 1,762 residents, of which 764 (43.4 %) were in Mariana and 998 (56.6 %) in Ouro Preto. For both cities, 51.9 % of the interviewees were female, with a predominance of the age range 35 to 59 years old (47.2 %). The prevalence of the SARS-CoV-2 infection was 5.5 % in both cities, 6.2 % in Ouro Preto, and 4.7 % in Mariana (p-value > 0.05). Conclusion: The study was effective to estimate the seroprevalence of infection by the virus and its findings will enable further analyses of the health conditions of the population related to social isolation and the risk of infection with SARS-CoV-2.

The COVID-19 pandemic has generated substantial changes in the lives of the population, such as increased physical inactivity, which can lead to being overweight and, consequently, repercussions on glucose homeostasis. A cross-sectional study based on the adult population of Brazil was conducted by stratified, multistage probability cluster sampling (October and December 2020). Participants were classified as physically active or inactive during leisure time according to the recommendations of the World Health Organization. HbA1c levels were categorized as normal (≤6.4%) or with glycemic changes (≥6.5%). The mediating variable was being overweight (overweight and obese). Descriptive, univariate, and multivariate logistic regression analyses examined the association between physical inactivity and glycemic changes. Mediation was analyzed using the Karlson–Holm–Breen method to verify the influence of being overweight on the association. We interviewed 1685 individuals, mostly women (52.4%), 35–59 years old (45.8%), race/ethnicity brown (48.1%), and overweight (56.5%). The mean HbA1c was 5.68% (95% CI: 5.58–5.77). Mediation analysis verified that physically inactive participants during leisure time were 2.62 times more likely to have high levels of HbA1c (OR: 2.62, 95% CI: 1.29–5.33), and 26.87% of this effect was mediated by over-weight (OR: 1.30: 95% CI: 1.06–1.57). Physical inactivity at leisure increases the chances of high levels of HbA1c, and part of this association can be explained by being overweight.

Background: A population study is an important tool that can be used to understand the actual epidemiological scenario of the Covid-19 in different territories, identify its magnitude, understand its transmission dynamics, and its demographic, geographical, and social distribution. Objective: The aim of this study was to determine the prevalence and dynamics of SARS-CoV-2 infection in the population of two Brazilian cities during the pandemic first wave and subsequent socioeconomic and health effects. Materials & methods: This paper described the methodological procedures adopted and the prevalence of the SARS-CoV-2 infection in the population. A household survey was conducted between October and December 2020, in two historic cities of Brazil's mining region. Anti-SARS-CoV-2 antibody was detected using the Wondfo® rapid test. The face-to-face interview consisted of administration of a questionnaire containing registration data, sociodemographic and economic variables, living habits, general health condition, mental health, sleep habits, and eating and nutrition. Results: We evaluated 1,762 residents, of which 764 (43.4%) were in Mariana and 998 (56.6%) in Ouro Preto. For both cities, 51.9% of the interviewees were female, with a predominance of the age range 35 to 59 years old (47.2%). The prevalence of the SARS-CoV-2 infection was 5.5% in all cities, 6.2% in Ouro Preto, and 4.7% in Mariana. The prevalence was similar between cities (P>0.05). Conclusion: The study was effective in verifying the seroprevalence of infection by the virus and its findings will enable further analyses of the health conditions of the population related to social isolation and the risk of infection with SARS-CoV-2.

Background: Accurate and rapid testing for COVID-19 is critical for effective disease management and control. The One-Step-COVID-2019-Test was developed as a rapid serological test to detect antibodies against SARS-CoV-2. Objective: To estimate the accuracy of the rapid serological test for COVID-19 using One-Step-COVID-2019. Methods: We conducted a population-based serological survey with a stratified sampling of 593 adults between October and December 2020, prior to mass vaccination and during a period of limited availability of rapid tests. Participants provided 7.5 mL of serum, which was tested using the One-Step-COVID-2019-Test for IgM-IgG antibodies without distinction, as well as an in-house ELISA for IgG against the spike protein. Statistical analysis accounted for sampling weights, with accuracy assessed through sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), Youden index, and kappa coefficient, using ELISA as the reference standard. McNemar’s test identified significant differences between the test results. Results: The ELISA-based prevalence of infection was 11.1%. The One-Step-COVID-2019-Test showed low sensitivity (27.0–30.8%) but high specificity (89.9–96.6%), with poor agreement (kappa: 0.290–0.337), particularly among asymptomatic individuals. Conclusions: The One-Step-COVID-2019 rapid test for COVID-19 demonstrated inadequate performance, characterized by low sensitivity and poor reliability, making it unsuitable for effective serological surveillance.

Background and Objectives: At the beginning of the Covid-19 pandemic, the absence of a national protocol for epidemiological surveillance and control hindered the understanding of the true prevalence of Covid-19 in Brazil. This study aimed to estimate the anti-SARS-CoV-2 antibodies prevalence and describe the serological profile according to socioeconomic, geographic, and health characteristics in Mariana and Ouro Preto municipalities, Minas Gerais. Methods: A cross-sectional population-based serological survey was conducted with 1,762 adults from October to December 2020. A qualitative immunochromatographic rapid test assessed infection; georeferencing and statistical inference analyses were performed. Results: The infection prevalence was 5.2%. Multivariate analysis revealed that lower per capita family income (≤ 0.5 minimum wage) (OR: 3.63; 95% CI: 1.70–7.76), higher density of occupants per room (≥ 1.0) (OR: 0.42; 95% CI: 0.23–0.76), and previous contact with suspected or confirmed cases of Covid-19 (OR: 2.58; 95% CI: 1.16–5.73) were significantly associated with seropositivity. Seropositive individuals reported higher frequencies of fatigue (14.8%), dyspnea (9.3%), ageusia (9.3%), and anosmia (8.8%), in addition to lower educational performance (p=0.024), lower per capita family income (p=0.018), and a greater number of comorbidities (p=0.041). A heterogenous geographic distribution was observed, with concentrations in census sectors with average incomes of one to three minimum wages. Conclusion: The study highlights a heterogeneous distribution of SARS-CoV-2 infections, with seropositive individuals predominantly coming from lower socioeconomic segments and presenting greater health vulnerabilities. These findings emphasize the need for targeted public health strategies and interventions to improve disease surveillance and mitigate health disparities in similar contexts.

The covid-19 pandemic has generated substantial changes in the lives of the population, such as increased physical inactivity, which can lead to overweight and, consequently, repercussions on glucose homeostasis. A population-based household epidemiological survey was conducted by stratified, multistage probability cluster sampling (October and December 2020) in Brazil. Participants were classified as physically active or inactive during leisure time according to the recommendations of the World Health Organization. HbA1c levels were categorized as normal (≤6.4%) or with glycemic changes (≥ 6.5%). The mediating variable was excess weight (overweight and obese). Multivariate logistic regression analyzes were performed to examine the association between physical inactivity and glycemic changes. Mediation was analyzed using the Karlson–Holm–Breen method to verify the influence of excess weight on the association. We interviewed 1,685 individuals, mostly women (52.4%), 35–59 years old (45.8%), race/ethnicity brown (48.1%), and excess weight (56.5%). The mean HbA1c was 5.68% (95% CI: 5.58-5.77). Individuals physically inactive were 2.62 times more likely to have glycemic alterations (OR:2.62.95% CI:1.29-5.33), and 26.87% of this association was mediated by excess weight (OR:1.30:95% CI:1.06-1.57). Physical inactivity in leisure time increases the chances of glycemic alterations, and part of this association can be explained by excess weight.