COVID Testing in the Workplace: Return to Work Testing in an Occupational Cohort

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Abstract

Background

The Omicron SARS-CoV-2 variant resulted in significant community-based transmission. Numerous occupational settings have employed surveillance testing strategies to minimize occupational exposure and return workers safely to work following isolation.

Methods

From an occupational COVID-19 testing program, we obtained longitudinal (February 2021-January 2022) saliva-based RT-qPCR results and starting December 27th, 2021, daily on-site molecular over-the-counter (OTC) nasal swab-based isothermal nucleic acid amplification test (molecular OTC; Cue Health COVID-19 test) results. We quantified the fraction of tests with PCR cycle threshold (Ct) values <30 on each day post detection from suspected and confirmed Omicron infections (n=37), compared results to molecular OTC testing, and measured workplace and household transmission. We evaluated return-to-work timing using a post-isolation, two-test threshold of Ct >30, or two negative molecular OTC tests over a 24 hour period, or a single PCR test >30 plus negative molecular OTC test.

Results

From the paired testing cohort, 37 (48%) individuals tested positive; all 37 were vaccinated. All individuals tested positive ≤1 day after a previous negative test, and 19 (51.3%) remained PCR-positive with Ct values <30 at day 5. While 3 (8.1%) remained PCR-positive with a Ct value <30 on day 10, no individuals remained PCR-positive on day 12. The average time to PCR clearance/return-to-work was 7.94 days (median=9.5 days). Time to clearance for those boosted (n=8; 7.75 days) and those not yet boosted (8.04 days) did not differ ( p =0.49). Peak viral load measured by PCR was 1.97 days from the initial positive test. There were no cases of transmission after returning to work.

Conclusions

A large percentage of individuals remain contagious at day 5 post first positive test based on serial PCR testing and can continue until day 12. Early discontinuation of isolation can utilize a two test framework separated by 24 hours. Rapid onsite tests may be useful.

Article activity feed

  1. SciScore for 10.1101/2022.02.09.22270653: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: Study oversight: In accordance with the guidelines, this work with de-identified samples was approved for research by the SUNY Downstate Institutional Review Board & Privacy Board under the title “Pilot program for instituting massive COVID19 surveillance screening in schools and the workplace (IRB#1603504-6).
    Sex as a biological variablenot detected.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    Software and Algorithms
    SentencesResources
    For whole genome sequencing, RNA was extracted and confirmed as SARS-CoV-2 positive by RT-qPCR with the Thermo Fisher TaqPath SARS-CoV-2 assay.
    Thermo Fisher TaqPath
    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: 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.

    Results from scite Reference Check: We found no unreliable references.


    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.