Seroprevalence of SARS-CoV-2 antibodies among 925 staff members in an urban hospital accepting COVID-19 patients in Osaka prefecture, Japan

  1. Tsutomu Nishida
  2. Hiromi Iwahashi
  3. Kazuhiro Yamauchi
  4. Noriko Kinoshita
  5. Yukiyoshi Okauchi
  6. Norihiro Suzuki
  7. Masami Inada
  8. Kinya Abe

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Abstract

The subclinical severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection rate in hospitals during the pandemic remains unclear. To evaluate the effectiveness of our hospital's current nosocomial infection control measures, we conducted a serological survey of anti-SARS-CoV-2 antibodies (immunoglobulin [Ig] G) among the staff of our hospital, which is treating coronavirus disease 2019 (COVID-19) patients.

The study design was cross-sectional. We measured anti-SARS-CoV-2 IgG in the participants using a laboratory-based quantitative test (Abbott immunoassay), which has a sensitivity and specificity of 100% and 99.6%, respectively. To investigate the factors associated with seropositivity, we also obtained some information from the participants with an anonymous questionnaire. We invited 1133 staff members in our hospital, and 925 (82%) participated. The mean age of the participants was 40.0 ± 11.8 years, and most were women (80.0%). According to job title, there were 149 medical doctors or dentists (16.0%), 489 nurses (52.9%), 140 medical technologists (14.2%), 49 healthcare providers (5.3%), and 98 administrative staff (10.5%). The overall prevalence of seropositivity for anti-SARS-CoV-2 IgG was 0.43% (4/925), which was similar to the control seroprevalence of 0.54% (16/2970) in the general population in Osaka during the same period according to a government survey conducted with the same assay. Seropositive rates did not significantly differ according to job title, exposure to suspected or confirmed COVID-19 patients, or any other investigated factors.

The subclinical SARS-CoV-2 infection rate in our hospital was not higher than that in the general population under our nosocomial infection control measures.

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  1. Version published to 10.1097/md.0000000000026433
  2. ScreenIT

    SciScore for 10.1101/2020.09.10.20191866: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The present study was conducted in accordance with the principles of the Declaration of Helsinki, and approval was obtained from the Institutional Review Board of Toyonaka Municipal Hospital (No. 2020–05–08).
    Consent: We obtained written informed consent from participants prior to the study.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    IgG antibodies against SARS-CoV-2 were detected using a laboratory-based quantitative assay (Abbott ARCHITECT○R SARS-CoV-2 IgG Assay; chemiluminescence microparticle immunoassay; sensitivity: 100%, specificity: 99.6%; Abbott Laboratories, IL, USA) performed on the Abbott Architect i4000SR (Abbott Diagnostics, IL, USA) at the Division of Clinical Laboratory in our hospital according to the manufacturer’s instructions.
    SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    IgG antibodies against SARS-CoV-2 were detected using a laboratory-based quantitative assay (Abbott ARCHITECT○R SARS-CoV-2 IgG Assay; chemiluminescence microparticle immunoassay; sensitivity: 100%, specificity: 99.6%; Abbott Laboratories, IL, USA) performed on the Abbott Architect i4000SR (Abbott Diagnostics, IL, USA) at the Division of Clinical Laboratory in our hospital according to the manufacturer’s instructions.
    Abbott Laboratories
    suggested: None
    Abbott Architect
    suggested: (Abbott ARCHITECT i1000sr System, RRID:SCR_019328)
    Abbott
    suggested: (Abbott, RRID:SCR_010477)
    Clinical Laboratory
    suggested: None
    The statistical analyses were performed with JMP statistical software (ver. 14.3, SAS Institute, Inc., Cary, NC, USA).
    SAS Institute
    suggested: (Statistical Analysis System, RRID:SCR_008567)

    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:
    This study has several limitations. First, we could not survey all the staff in our hospital; thus, the prevalence found in this study may not be exact. However, more than 80% of the hospital staff in our hospital, including staff in all jobs, were involved in the present study. We believe the result obtained from this study is very close to the exact value. Second, there is an issue with serological tests. Serological tests do not detect the virus itself and instead reflect the body’s immune response to infection by the virus. Therefore, false-positive results are possible due to cross-reactivity with pre-existing antibodies and other reasons. The specificity of the immunoassay used in this study is reported to be 99.6%, indicating that there could have been four false-positive cases in every 1000 subjects tested 11. Although we should consider this limitation of the serological test, we can assume at the very least that the subclinical SARS-CoV-2 infection rate is less than 0.43% in our hospital. In conclusion, we found that the subclinical SARS-CoV-2 infection rate in our hospital, which treats COVID-19 patients during the pandemic in Japan, is not higher than that in the general population in the same area during the same period. Timely serological screening of a large cohort is essential for achieving control during the pandemic 12. Furthermore, hospital-based antibody screening could also help us evaluate and monitor infection control. A longitudinal survey of serum ant...

    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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  3. Version published to 10.1101/2020.09.10.20191866v1 on medRxiv