SARS-CoV-2 serosurvey in health care workers of the Veneto Region

  1. Mario Plebani
  2. Andrea Padoan
  3. Ugo Fedeli
  4. Elena Schievano
  5. Elena Vecchiato
  6. Giuseppe Lippi
  7. Giuliana Lo Cascio
  8. Stefano Porru
  9. Giorgio Palù

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Abstract

Objectives

The ongoing outbreak of coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) poses formidable challenges to all health care systems. Serological assays may be used for improving disease management when appropriately applied, for investigating the antibody responses mounted against SARS-CoV-2 infection and for assessing its real prevalence. Although testing the whole population is impractical, well-designed serosurveys in selected subpopulations in specific risk groups may provide valuable information. We evaluated the prevalence of SARS-CoV-2 infection in health care workers (HCW) who underwent molecular testing with reverse transcription real-time polymerase chain reaction (rRT-PCR) in the main hospitals of the Veneto Region of Italy by measuring specific antibodies (Abs).

Methods

Both immunoglobulin (Ig)M and IgG antibodies against SARS-Cov-2 S-antigen and N-protein were measured using a validated chemiluminescent analytical system (CLIA) called Maglumi™ 2000 Plus (New Industries Biomedical Engineering Co., Ltd [Snibe], Shenzhen, China).

Results

A total of 8,285 HCW were tested. SARS-CoV-2 specific antibodies (IgM, IgG or both) were detectable in 378 cases (4.6%, 95% CI 4.1–5.0%). Seroconversion was observed in 4.4% of women vs. 5.0% of men, but this difference was not significant. Although detectable antibodies were found in all HCW who developed severe COVID-19 infection (100%), lower seropositivity was found in mild disease (83%) and the lowest prevalence (58%) was observed in asymptomatic subjects.

Conclusions

Seroprevalence surveys are of utmost importance for understanding the rate of population that has already developed antibodies against SARS-CoV-2. The present study defined precisely the circulation of SARS-CoV-2 in a cohort of HCW in the Veneto Region, with its prevalence (4.6%) reflecting a relatively low circulation. Symptomatic individuals or those hospitalized for medical care were 100% antibody positive, whilst Abs were only detectable in 58% of asymptomatic carriers.

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  1. Version published to 10.1515/cclm-2020-1236
  2. ScreenIT

    SciScore for 10.1101/2020.07.23.20160457: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: This study was approved by the Regional Committee for Bioethics (prot. n. 178357) and the Ethics Committee of the University Hospital of Verona (prot. n. 22851) and all subjects recruited to the study expressed an informed consent for being enrolled.
    Consent: This study was approved by the Regional Committee for Bioethics (prot. n. 178357) and the Ethics Committee of the University Hospital of Verona (prot. n. 22851) and all subjects recruited to the study expressed an informed consent for being enrolled.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Ltd [Snibe], Shenzhen, China) is a chemiluminescent analytical system (CLIA) for the detection of both IgM and IgG antibodies against SARS-Cov-2 S-antigen and N-protein.
    SARS-Cov-2
    suggested: None
    S-antigen
    suggested: None
    N-protein
    suggested: None
    Software and Algorithms
    SentencesResources
    Subjects included in the study: This multicenter study involved several Structures of the National Healthcare Service of the Veneto Region, in which was reported an early cluster of SARS-CoV-2 infection in Italy on February 21th, 2020.
    National Healthcare
    suggested: None

    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:
    The present study has some limitations. First, the study population cannot be considered representative of the whole healthcare workforce in the Veneto Region, and a selection bias should be necessarily recognized. Second, the relationships of currently measured antibodies with neutralizing activity against SARS-CoV-2 were not evaluated. A body of evidence, however, demonstrates that antibodies targeting different domains of S protein, including S1, RBD and S2, may all contribute to virus neutralization (21, 22). Finally, follow-up data on subjects with detectable SARS-CoV-2 antibodies are not yet available as this follow-up requires some more months to better understand the duration of immune response and protection from reinfection.

    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

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  3. Version published to 10.1101/2020.07.23.20160457 on medRxiv