Prevalence of SARS-CoV-2 infection among asymptomatic healthcare workers in greater Houston: a cross-sectional analysis of surveillance data from a large healthcare system

  1. Farhaan S. Vahidy
  2. H. Dirk Sostman
  3. David W. Bernard
  4. Marc L. Boom
  5. Ashley L. Drews
  6. Paul Christensen
  7. Jeremy Finkelstein
  8. Bita A. Kash
  9. Robert A. Phillips
  10. Roberta L. Schwartz

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Abstract

Objective

To determine the prevalence of SARS-CoV-2 infection among asymptomatic COVID-19 facing and non-COVID-19 facing Healthcare Workers (HCWs), with varying job categories across different hospitals.

Design

Cross-sectional analysis of a healthcare system surveillance program that included asymptomatic clinical (COVID-19 facing and non-COVID-19 facing), and non-clinical HCWs. A convenience sample of asymptomatic community residents (CR) was also tested. Proportions and 95% confidence Intervals (CI) of SARS-CoV-2 positive HCWs are reported. Proportional trend across HCW categories was tested using Chi Square trend test. Logistic regression model-based likelihood estimates of SARS-CoV-2 prevalence among HCWs with varying job functions and across different hospitals are reported as adjusted odds ratios (aOR) and CI.

Setting

Healthcare system comprising one tertiary care academic medical center and six large community hospitals across Greater Houston and a community sample.

Participants

2,872 self-reported asymptomatic adult (> 18 years) HCWs and CRs.

Exposure

Clinical HCWs in COVID-19 and non-COVID-19 units, non-Clinical HCWs, and CRs. Job categories of Nursing, Providers, Allied Health, Support, and Administration / Research. Seven hospitals in the healthcare system.

Main Outcomes

Positive reverse transcriptase polymerized chain reaction (RT-PCR) test for SARS-CoV-2

Results

Among 2,872 asymptomatic HCWs and CRs, 3.9% (CI: 3.2 – 4.7) tested positive for SARS-CoV-2. Mean (SD) age was 40.9 (11.7) years and 73% were females. Among COVID-19 facing HCWs 5.4% (CI: 4.5 – 6.5) were positive, whereas 0.6% (CI: 0.2 – 1.7%) of non COVID-19 facing HCWs and none of the non-clinical HCWs or CRs were positive ( P trend < 0.001). Among COVID-19 facing HCWs, SARS-CoV-2 positivity was similar for all job categories (p = 0.74). However, significant differences in positivity were observed across hospitals.

Conclusions and Relevance

Asymptomatic HCWs with COVID-19 patient exposure had a higher rate of SARS-CoV-2 positive testing than those not routinely exposed to COVID-19 patients and those not engaged in patient care. Among HCWs with routine COVID-19 exposure, all job types had relatively similar infection rates. These data can inform hospital surveillance and infection control practices for patient-facing job classifications and suggest that general environmental exposure within hospitals is not a significant source of asymptomatic SARS-CoV-2 infection.

What is already known on this topic

  • A sizeable proportion of individuals who contract the novel Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) can remain largely asymptomatic.

  • Though such individuals may not develop symptoms, they continue to shed enough viral particles to trigger positive reverse transcriptase polymerized chain reaction (RT PCR) test for SARS-CoV-2

  • Prior reports on proportion of asymptomatic SARS-CoV-2 individuals are highly variable with positivity ranging across < 1% to 36%

  • Asymptomatic SARS-CoV-2 infection among healthcare workers is specifically critical to understand

What this study adds

  • This study demonstrates that overall rate of SARS-CoV-2 infection among asymptomatic healthcare workers in a large healthcare system of a metropolitan city in the United States was 3.9%

  • The rate of SARS-CoV-2 infection among healthcare workers who provided direct care to COVID-19 patients was 5.4% whereas it was 0.6% among those healthcare workers who did not provide direct care to COVID-19 patients

  • There was no difference in SARS-CoV-2 positivity rate for different job categories of healthcare workers who provided direct care to COVID-19 patients

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  1. ScreenIT

    SciScore for 10.1101/2020.05.21.20107581: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board Statementnot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power AnalysisFirst phase testing was planned for at least 2,500 patients that provided > 90% power to test the anticipated difference with type I error rate of 5%.
    Sex as a biological variablenot detected.

    Table 2: Resources

    No key resources detected.

    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: An explicit section about the limitations of the techniques employed in this study was not found. We encourage authors to address study limitations.

    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.

  2. Version published to 10.1101/2020.05.21.20107581v1 on medRxiv