Efficacy of FFP3 respirators for prevention of SARS-CoV-2 infection in healthcare workers

  1. Mark Ferris  Is a corresponding author
  2. Rebecca Ferris
  3. Chris Workman
  4. Eoin O'Connor
  5. David A Enoch
  6. Emma Goldesgeyme
  7. Natalie Quinnell
  8. Parth Patel
  9. Jo Wright
  10. Geraldine Martell
  11. Christine Moody
  12. Ashley Shaw
  13. Christopher J R Illingworth
  14. Nicholas J Matheson
  15. Michael P Weekes  Is a corresponding author
  1. University of Cambridge Occupational Health and Safety Service, United Kingdom
  2. Cambridge University Hospitals NHS Trust, United Kingdom
  3. School of Clinical Medicine, University of Cambridge, United Kingdom
  4. Cambridge Biomedical Campus, United Kingdom
  5. University of Cambridge, United Kingdom
  6. Cambridge Institute for Medical Research, University of Cambridge, United Kingdom

Abstract

Background: Respiratory protective equipment recommended in the UK for healthcare workers (HCWs) caring for patients with COVID-19 comprises a fluid resistant surgical mask (FRSM), except in the context of aerosol generating procedures (AGPs). We previously demonstrated frequent pauci- and asymptomatic SARS-CoV-2 infection HCWs during the first wave of the COVID-19 pandemic in the UK, using a comprehensive PCR-based HCW screening programme (Rivett et al., 2020; Jones et al., 2020).

Methods: Here, we use observational data and mathematical modelling to analyse infection rates amongst HCWs working on 'red' (COVID-19) and 'green' (non-COVID-19) wards during the second wave of the pandemic, before and after the substitution of filtering face piece 3 (FFP3) respirators for FRSMs.

Results: Whilst using FRSMs, HCWs working on red wards faced an approximately 31-fold (and at least 5-fold) increased risk of direct, ward-based infection. Conversely, after changing to FFP3 respirators, this risk was significantly reduced (52-100% protection).

Conclusions: FFP3 respirators may therefore provide more effective protection than FRSMs for healthcare workers caring for patients with COVID-19, whether or not AGPs are undertaken.

Funding: Wellcome Trust, Medical Research Council, Addenbrooke's Charitable Trust, NIHR Cambridge Biomedical Research Centre, NHS Blood and Transfusion, UKRI.

Data availability

All data generated or analysed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1 and 3, and their supplements. Figure 2 source data is included in a table in the main text.

Article and author information

Author details

  1. Mark Ferris

    University of Cambridge Occupational Health and Safety Service, Cambridge, United Kingdom
    For correspondence
    mark.ferris@addenbrookes.nhs.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0001-5040-4263
  2. Rebecca Ferris

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  3. Chris Workman

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  4. Eoin O'Connor

    School of Clinical Medicine,, School of Clinical Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-6846-6881
  5. David A Enoch

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  6. Emma Goldesgeyme

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  7. Natalie Quinnell

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  8. Parth Patel

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  9. Jo Wright

    Occupational Health and Wellbeing, Cambridge Biomedical Campus, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  10. Geraldine Martell

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  11. Christine Moody

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  12. Ashley Shaw

    Cambridge University Hospitals NHS Trust, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
  13. Christopher J R Illingworth

    MRC Biostatistics Unit, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-0030-2784
  14. Nicholas J Matheson

    Department of Medicine, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0002-3318-1851
  15. Michael P Weekes

    Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    For correspondence
    mpw1001@cam.ac.uk
    Competing interests
    The authors declare that no competing interests exist.
    ORCID icon "This ORCID iD identifies the author of this article:" 0000-0003-3196-5545

Funding

Wellcome Trust (108070/Z/15/Z)

  • Michael P Weekes

Addenbrooke's Charitable Trust, Cambridge University Hospitals

  • Michael P Weekes

NIHR Cambridge Biomedical Research Centre

  • Michael P Weekes

Medical Research Council (MR/P008801/1)

  • Nicholas J Matheson

NHS Blood and Transfusion (WPA15-02)

  • Nicholas J Matheson

UK Research and Innovation (MR/V038613/1)

  • Christopher J R Illingworth

Medical Research Council (MC_UU_00002/11)

  • Christopher J R Illingworth

Medical Research Council (MC_UU_12014)

  • Christopher J R Illingworth

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Ethics

Human subjects: This study was conducted as a service evaluation of the CUHNFT staff testing services and PPE policy (CUHNFT clinical project ID3738). As a study of healthcare-associated infections, this investigation is exempt from requiring ethical approval under Section 251 of the NHS Act 2006 (see also the NHS Health Research Authority algorithm, available at http://www.hra-decision-tools.org.uk/research/, which concludes that no formal ethical approval is required).

Reviewing Editor

  1. Jos W Van der Meer, Radboud University Medical Centre, Netherlands

Publication history

  1. Received: June 18, 2021
  2. Accepted: November 7, 2021
  3. Accepted Manuscript published: November 16, 2021 (version 1)
  4. Version of Record published: December 1, 2021 (version 2)

Copyright

© 2021, Ferris et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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  1. Mark Ferris
  2. Rebecca Ferris
  3. Chris Workman
  4. Eoin O'Connor
  5. David A Enoch
  6. Emma Goldesgeyme
  7. Natalie Quinnell
  8. Parth Patel
  9. Jo Wright
  10. Geraldine Martell
  11. Christine Moody
  12. Ashley Shaw
  13. Christopher J R Illingworth
  14. Nicholas J Matheson
  15. Michael P Weekes
(2021)
Efficacy of FFP3 respirators for prevention of SARS-CoV-2 infection in healthcare workers
eLife 10:e71131.
https://doi.org/10.7554/eLife.71131
  1. Further reading

Further reading

    1. Epidemiology and Global Health
    2. Medicine
    Nick K Jones, Lucy Rivett ... Michael P Weekes
    Research Advance Updated

    Previously, we showed that 3% (31/1032)of asymptomatic healthcare workers (HCWs) from a large teaching hospital in Cambridge, UK, tested positive for SARS-CoV-2 in April 2020. About 15% (26/169) HCWs with symptoms of coronavirus disease 2019 (COVID-19) also tested positive for SARS-CoV-2 (Rivett et al., 2020). Here, we show that the proportion of both asymptomatic and symptomatic HCWs testing positive for SARS-CoV-2 rapidly declined to near-zero between 25th April and 24th May 2020, corresponding to a decline in patient admissions with COVID-19 during the ongoing UK ‘lockdown’. These data demonstrate how infection prevention and control measures including staff testing may help prevent hospitals from becoming independent ‘hubs’ of SARS-CoV-2 transmission, and illustrate how, with appropriate precautions, organizations in other sectors may be able to resume on-site work safely.

    1. Epidemiology and Global Health
    2. Medicine
    Lucy Rivett, Sushmita Sridhar ... Michael P Weekes
    Research Article Updated

    Significant differences exist in the availability of healthcare worker (HCW) SARS-CoV-2 testing between countries, and existing programmes focus on screening symptomatic rather than asymptomatic staff. Over a 3 week period (April 2020), 1032 asymptomatic HCWs were screened for SARS-CoV-2 in a large UK teaching hospital. Symptomatic staff and symptomatic household contacts were additionally tested. Real-time RT-PCR was used to detect viral RNA from a throat+nose self-swab. 3% of HCWs in the asymptomatic screening group tested positive for SARS-CoV-2. 17/30 (57%) were truly asymptomatic/pauci-symptomatic. 12/30 (40%) had experienced symptoms compatible with coronavirus disease 2019 (COVID-19)>7 days prior to testing, most self-isolating, returning well. Clusters of HCW infection were discovered on two independent wards. Viral genome sequencing showed that the majority of HCWs had the dominant lineage B∙1. Our data demonstrates the utility of comprehensive screening of HCWs with minimal or no symptoms. This approach will be critical for protecting patients and hospital staff.