COVID-19 Seroprevalence among Healthcare Workers of a Large COVID-19 Hospital in Rome Reveals Strengths and Limits of Two Different Serological Tests

  1. Giuseppe Vetrugno
  2. Daniele Ignazio La Milia
  3. Floriana D’Ambrosio
  4. Marcello Di Pumpo
  5. Roberta Pastorino
  6. Stefania Boccia
  7. Rosalba Ricci
  8. Fabio De-Giorgio
  9. Michela Cicconi
  10. Federica Foti
  11. Domenico Pascucci
  12. Francesco Castrini
  13. Elettra Carini
  14. Andrea Cambieri
  15. Maria Elena D’Alfonso
  16. Gennaro Capalbo
  17. Massimo Fantoni
  18. Umberto Moscato
  19. Domenico Staiti
  20. Francesco Maria De Simone
  21. Filippo Berloco
  22. Gianfranco Damiani
  23. Maurizio Zega
  24. Paola Cattani
  25. Brunella Posteraro
  26. Maurizio Sanguinetti
  27. Patrizia Laurenti

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Abstract

Healthcare workers are at the forefront against COVID-19, worldwide. Since Fondazione Policlinico Universitario A. Gemelli (FPG) IRCCS was enlisted as a COVID-19 hospital, the healthcare workers deployed to COVID-19 wards were separated from those with limited/no exposure, whereas the administrative staff were designated to work from home. Between 4 June and 3 July 2020, an investigation was conducted to evaluate the seroprevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin (IgG) antibodies among the employees of the FPG using point-of-care (POC) and venous blood tests. Sensitivity, specificity, and predictive values were determined with reverse-transcription polymerase chain reaction on nasal/oropharyngeal swabs as the diagnostic gold standard. The participants enrolled amounted to 4777. Seroprevalence was 3.66% using the POC test and 1.19% using the venous blood test, with a significant difference (p < 0.05). The POC test sensitivity and specificity were, respectively, 63.64% (95% confidence interval (CI): 62.20% to 65.04%) and 96.64% (95% CI: 96.05% to 97.13%), while those of the venous blood test were, respectively, 78.79% (95% CI: 77.58% to 79.94%) and 99.36% (95% CI: 99.07% to 99.55%). Among the low-risk populations, the POC test’s predictive values were 58.33% (positive) and 98.23% (negative), whereas those of the venous blood test were 92.86% (positive) and 98.53% (negative). According to our study, these serological tests cannot be a valid alternative to diagnose COVID-19 infection in progress.

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  1. Version published to 10.3390/ijerph18052650
  2. ScreenIT

    SciScore for 10.1101/2021.01.08.21249445: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementIRB: The study was approved by the FPG Ethics Committee (number ID 3253) and participants signed an informed consent before their inclusion in the study.
    Consent: The study was approved by the FPG Ethics Committee (number ID 3253) and participants signed an informed consent before their inclusion in the study.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    Detection of anti-SARS-CoV-2 antibodies in blood samples: Two serological tests were used to detect SARS-CoV-2 specific antibodies in participants’ blood samples.
    anti-SARS-CoV-2
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistical analyses were carried out using a software for the construction of the general basic dataset (Microsoft Excel for Mac Version 16.35), and specific for the inferential statistical analysis (Stata Corp 4905 Lakeway, College Station, USA Stata / IC 14.2 for Mac (64-bit Intel), Revision 29 Jan 2018).
    Microsoft Excel
    suggested: (Microsoft Excel, RRID:SCR_016137)

    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:
    Our study had several limitations. The sample was not drawn randomly and the estimation of the seroprevalence was also subject to other potential sampling bias, due to the voluntarily enrolling procedure. Moreover, the sensitivity of the serological test could be biased because it depends on the test time from the onset of disease. Samples collected from infected individuals outside the time window of antibody response could produce false negatives and, therefore, the observed seroprevalence in our study could potentially underestimate the true prevalence of the disease. Another limitation of the study could consist in the COVID-19 case detection strategy. In fact, to ascertain the exact number of COVID-19 cases among HCWs, a systematic and periodic (ideally every 14 days) screening with RT-PCR from NOS samples should be performed. However, this was not sustainable during the emergency due to lack of resources. Owing to the cross-sectional design of this study, the dynamic changes of antibody titre in infected individuals over time were not evaluated. Further studies, especially with long-term follow-up, will be needed in the future to assess the value of serological tests, considering their major public health implications.

    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 10.1101/2021.01.08.21249445v2 on medRxiv
  4. Version published to 10.1101/2021.01.08.21249445v1 on medRxiv