Healthcare worker risk of COVID-19: A 20-month analysis of protective measures from vaccination and beyond

  1. Annalee Yassi
  2. Stephen Barker
  3. Karen Lockhart
  4. Jennifer M. Grant
  5. Arnold Ikedichi Okpani
  6. Stacy Sprague
  7. Muzimkhulu Zungu
  8. Stan Lubin
  9. Chad Kim Sing

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Abstract

Background: As the COVID-19 pandemic continues and new variants such as Omicron emerge, we aimed to re-evaluate vaccine effectiveness as well as impacts of rigorously implemented infection control, public health and occupational health measures in protecting healthcare workers (HCWs). Methods: Following a cohort of 21,242 HCWs in Vancouver, British Columbia, Canada, for 20 months since the pandemic started, we used Cox regression and test-negative design to examine differences in SARS-COV-2 infection rates compared to community counterparts, and within the HCW workforce, assessing the role of occupation, testing accessibility, vaccination rates, and vaccine effectiveness over time. Results: Nurses, allied health professionals and medical staff in this jurisdiction had a significantly lower rate of infection compared to their age-group community counterparts, at 47.4, 41.8, and 55.3% reduction respectively; controlling for vaccine-attributable reductions, the protective impact was still substantial, at 33.4, 28.0, and 36.5% respectively. Licensed practical nurses and care aides had the highest risk of infection among HCWs, more than double that of medical staff. However, even considering differences in vaccination rates, no increase in SARS-CoV-2 infection was found compared to community rates, with combined protective measures beyond vaccination associated with a 17.7% reduced SARS-COV-2 rate in the VCH workforce overall. There was also no evidence of waning immunity within at least 200 days after second dose. Conclusion: Rigorously implemented occupational health, public health and infection control measures results in a well-protected healthcare workforce with infection rates at or below rates in community counterparts. Greater accessibility of vaccination worldwide is essential; however, as implementing measures to protect this workforce globally also requires considerable health system strengthening in many jurisdictions, we caution against overly focusing on vaccination to the exclusion of other crucial elements for wider protection of HCWs, especially in facing ongoing mutations which may escape current vaccines.

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  1. ScreenIT

    SciScore for 10.1101/2021.12.02.21267190: (What is this?)

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

    Table 1: Rigor

    NIH rigor criteria are not applicable to paper type.

    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: We detected the following sentences addressing limitations in the study:
    Also Alhumaid et al. (50) documented that compliance with infection control in healthcare is associated with non-availability of resources, high workload and time limitation, as well as risk perception, caring for patients with history of infectious disease. Thus, it is important to stress that the lack of increased risk for HCWs in VCH should not be generalized to other jurisdictions where PPE and other infection control supplies may not be as easily accessible to all HCWs, or staff shortages result in breaches in proper protocols essential for staff and patient protection. Rather, the findings should provide reassurance that when evidence-based policies and procedures are implemented, revised as needed, with repeat educational messaging and rigorously monitored infection rates, this crucially important workforce can indeed be protected.

    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.

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  2. Version published to 10.1101/2021.12.02.21267190v2 on medRxiv
  3. Version published to 10.1101/2021.12.02.21267190v1 on medRxiv