Assessment of initial SARS-CoV-2 seroprevalence in the most affected districts in the municipality of São Paulo, Brazil.

BACKGROUND: São Paulo city has been one of the regions most affected by the COVID-19 pandemic in Brazil. Frequent asymptomatic and oligosymptomatic infections and poor access to diagnostic tests make serosurveys crucial to monitor the magnitude of the epidemic and to inform public health policies, such as vaccination plans. OBJECTIVES: To estimate, early in the epidemic, the seroprevalence of antibodies to SARS-CoV-2 in adults living in the six most affected districts in São Paulo city, and to assess potential associated risk factors. METHODS: This was a cross-sectional population-based survey of 1,152 households randomly selected from 72 census tracts. During the period May 4-12, 2020, 463 participants completed a questionnaire on sociodemographic characteristics and history of symptoms in the past two weeks, and provided a blood sample. Prevalence of SARS-CoV-2 antibodies was the outcome of interest and was estimated based on results of two immunoassays, Maglumi SARS-CoV-2 chemiluminescence assay Immunoglobulin (Ig) M (IgM) and IgG, and Roche electrochemiluminescence assay total Ig. Serum samples reactive to either assay were considered positive. RESULTS: Weighted overall seroprevalence was 6% (95%CI 3.9-8.3%). No association was observed between seropositivity and sex, age group or education level. Participants who reported black and brown skin color showed a 2.7 fold higher prevalence than people with white skin (p = 0.007). Among the 30 seropositive individuals, 14 (46.6%) reported no COVID-19 compatible symptoms in the past two weeks. CONCLUSION: This study represents the first assessment of SARS-CoV-2 seroprevalence in the city of São Paulo and 6% is the baseline estimate of a series of population-based seroprevalence surveys. Serological screening using sound serological assays is the key tool to monitoring temporal and geographic changes in the spread of the virus through an important epicenter of the COVID-19 pandemic in Brazil. Ultimately, it may inform prevention and control efforts.

Critical preparedness and operational response actions directed for the acute and post-acute COVID-19 pandemic in Brazil: the experience of a nationwide outpatient healthcare group.

ABSTRACT: While the new Coronavirus Disease 2019 (COVID-19) pandemic rapidly spread across the world, South America was reached later in relation to Asia, Europe and the United States of America (USA). Brazil concentrates now the largest number of cases in the continent and, as the disease speedily progressed throughout the country, prompt and challenging operational strategies had to be taken by institutions caring for COVID-19 and non-COVID-19 patients in order to assure optimal workflows, triage, and management. Although hospitals in the USA, Europe and Asia have shared their experience on this subject, little has been discussed about such strategies in South America or by the perspective of outpatient centers, which are paramount in the radiology field. This article shares the guidelines adopted early in the pandemic by a nationwide outpatient healthcare center composed by a network of more than 200 patient service centers and nearly 2,000 radiologists in Brazil, discussing operational and patient management strategies, staff protection, changes adopted in the fellowship program, and the effectiveness of such measures.