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

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Abstract

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 São 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.

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  1. SciScore for 10.1101/2020.06.29.20142331: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementConsent: After obtaining informed consent from the participant, the team applied a structured questionnaire to gather information on sociodemographic characteristics and occurrence of COVID-19-related symptoms in the previous two weeks.
    IACUC: The study was approved by the Fleury Institutional Ethical Committee (CAAE 31032620.0.0000.5474).
    RandomizationTo allow for non-contact and refusals, 1049 households were randomly selected and surveyed.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    The recombinant antigens containing the nucleoprotein and a peptide from the spike protein of SARS-CoV-2 were conjugated with FITC and immobilized on anti-FITC antibody-conjugated magnetic particles.
    anti-FITC
    suggested: None
    Alkaline phosphatase-conjugated anti-human IgG and IgM was used as the detection antibody.
    anti-human IgG
    suggested: None
    Software and Algorithms
    SentencesResources
    The results of analyzing of these samples led to the following reference values: IgG: reagent >1.1 UA/mL, indeterminate 0.9 to 1.1 UA/mL, non-reagent <0.9 UA/mL; and IgM: reagent >1.0 UA/mL, indeterminate 0.7 to 1.0 UA/mL, non-reagent <0.7 UA/mL.
    IgG
    suggested: (DSHB Cat# LEP100 IgG, RRID:AB_528124)
    STATA version 14 (StataCorp, College Station, TX, USA) was used for all statistical analyses.
    STATA
    suggested: (Stata, RRID:SCR_012763)
    StataCorp
    suggested: (Stata, RRID:SCR_012763)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).


    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    There are some limitations to the study. First, since it was a cross-sectional study, temporal associations cannot be established and data are lacking on variables related to the epidemiology of SARS-CoV-2, such as the history of exposure and severity of symptoms. Second, refusal bias may have been introduced as a result of non-response, which occurred mainly due to non-cooperation by the managers of some residential blocks and to residents’ unwillingness to donate blood. Third, we have not included children or young people under 18 years due to logistic restrictions. Last, the statistical power may have been insufficient to detect differences between subgroups. However, we believe that these issues have not affected our findings significantly, considering that our results are consistent with several worldwide reports that showed low prevalence of SARS-CoV-2 infection in the general population even in highly affected regions [12,13,15]. In conclusion, the overall exposure to SARS-CoV-2 in the general population in the research areas is low, indicating that a significant proportion of this population could still be infected. Following these initial results, a series of six monthly point-prevalence serosurveys, using similar methodology and the same testing method, has been initiated. By monitoring the SARS-CoV-2 seroprevalence in a population-representative sample, as well as the ongoing pandemic in São Paulo City, high-risk groups and areas may be identified which will help g...

    Results from TrialIdentifier: No clinical trial numbers were referenced.


    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.


    Results from JetFighter: We did not find any issues relating to colormaps.


    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

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