ABSTRACT 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.

Abstract Background Hepatitis E virus (HEV) can cause chronic infection with rapid progression to liver cirrhosis in immunocompromised patients. HEV seroprevalence in patients with Schistosoma mansoni in Brazil is unknown. We evaluated the prevalence of past or present HEV infection in schistosomiasis patients in Recife, Pernambuco, Brazil. A total of 80 patients with Schistosoma mansoni were consecutively enrolled in a cross-sectional study. Serum samples were tested for the presence of anti-HEV IgG antibodies by enzyme immunoassay (Wantai anti-HEV IgG, Beijing, China) and for the presence of HEV RNA using real time reverse transcriptase-polymerase chain reaction with primers targeting the HEV ORF2 and ORF3. Clinical and laboratory tests as well as abdominal ultrasound were performed at the same day of blood collection. Results Anti-HEV IgG was positive in 18.8% (15/80) of patients with SM. None of the samples tested positive for anti-HEV IgM or HEV-RNA. Patients with anti-HEV IgG positive presented higher levels of alanine aminotranferase (p = 0.048) and gama-glutamil transferase (p = 0.022) when compared to patients without anti-HEV IgG antibodies. Conclusion This study demonstrates that the seroprevalence of HEV is high in patients with Schistosoma mansoni in Northeastern of Brazil. Past HEV infection is associated with higher frequency of liver enzymes abnormalities. HEV infection and its role on the severity of liver disease should be further investigated among patients with Schistosoma mansoni.