SARS-CoV-2 seroprevalence in the municipality of Sao Paulo, Brazil, ten weeks after the first reported case

A population-based household survey was performed to estimate the prevalence of IgM and IgG to SARS-CoV-2 in residents of six districts in Sao Paulo City, Brazil. Serum samples collected from 299 randomly-selected adults and 218 cohabitants (N=517) were tested by chemiluminescence immunoassay ten weeks after the first reported case. Weighted overall seroprevalence was 4.7% (95% CI 3.0-6.6%). The low seroprevalence suggests that most of this population could still be infected. Serial serosurveys were initiated aiming to monitor the progress of the ongoing pandemic throughout the entire city. This may help inform public health authority decisions regarding prevention and control strategies. ### Competing Interest Statement Authors associated with Grupo Fleury (C.F.H.G., M.C.P., E.R.) and Ibope Inteligencia (M.C.N.) disclose the following potential conflict of interest: the two organizations are co-funding the project by providing their services at or below cost. These include data and blood sample collection and laboratory tests. The companies sell these services in the market and might profit from the publicity generated by the results of this research. B.H.T., M.C.G.P.A. and F.C.R. declare no conflict of interest ### Funding Statement The study received funding from Instituto Semeia, Grupo Fleury and Ibope Inteligencia. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study was approved by the Fleury Institutional Ethical Committee (CAAE 31032620.0.0000.5474). All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The datasets analyzed during the current study are available from the corresponding author on reasonable request.