Differential occupational risks to healthcare workers from SARS-CoV-2 observed during a prospective observational study
- University of Oxford, United Kingdom
- Oxford University Hospitals, United Kingdom
- Nuffield Department of Medicine, University of Oxford, United Kingdom
- Oxford University Hospitals NHS Foundation Trust, United Kingdom
- NIHR Oxford Biomedical Research Centre, University of Oxford, United Kingdom
- Oxford University, United Kingdom
- Target Discovery Institute, University of Oxford, United Kingdom
Abstract
We conducted voluntary Covid-19 testing programmes for symptomatic and asymptomatic staff at a UK teaching hospital using naso-/oro-pharyngeal PCR testing and immunoassays for IgG antibodies. 1128/10,034(11.2%) staff had evidence of Covid-19 at some time. Using questionnaire data provided on potential risk-factors, staff with a confirmed household contact were at greatest risk (adjusted odds ratio [aOR] 4.82 [95%CI 3.45-6.72]). Higher rates of Covid-19 were seen in staff working in Covid-19-facing areas (22.6% vs. 8.6% elsewhere) (aOR 2.47 [1.99-3.08]). Controlling for Covid-19-facing status, risks were heterogenous across the hospital, with higher rates in acute medicine (1.52 [1.07-2.16]) and sporadic outbreaks in areas with few or no Covid-19 patients. Covid-19 intensive care unit staff were relatively protected (0.44 [0.28-0.69]), likely by a bundle of PPE-related measures. Positive results were more likely in Black (1.66 [1.25-2.21]) and Asian (1.51 [1.28-1.77]) staff, independent of role or working location, and in porters and cleaners (2.06 [1.34-3.15]).
Data availability
The data studied are available from the Infections in Oxfordshire Research Database (https://oxfordbrc.nihr.ac.uk/research-themes-overview/antimicrobial-resistance-and-modernising-microbiology/infections-in-oxfordshire-research-database-iord/), subject to an application and research proposal meeting the ethical and governance requirements of the Database. For further details on how to apply for access to the data and for a research proposal template please email iord@ndm.ox.ac.uk.
Article and author information
Author details
Bernadette C Young
Philip George Drennan
Alexander J Mentzer
Funding
UK Government: Department of Health and Social Care
- David W Eyre
- Sheila F Lumley
- Denise O'Donnell
- Mark Campbell
- Elizabeth Sims
- Elaine Lawson
- Fiona Warren
- Tim James
- Stuart Cox
- Alison Howarth
- George Doherty
- Stephanie B Hatch
- James Kavanagh
- Kevin K Chau
- Philip W Fowler
- Jeremy Swann
- Denis Volk
- Fan Yang-Turner
- Nicole Stoesser
- Philippa C Matthews
- Maria Dudareva
- Timothy Davies
- Robert H Shaw
- Leon Peto
- Louise O Downs
- Alexander Vogt
- Ali Amini
- Bernadette C Young
- Philip George Drennan
- Alexander J Mentzer
- Donal T Skelly
- Fredrik Karpe
- Matt J Neville
- Monique Andersson
- Andrew J Brent
- Nicola Jones
- Lucas Martins Ferreira
- Thomas Christott
- Brian D Marsden
- Sarah Hoosdally
- Richard Cornall
- Derrick W Crook
- David I Stuart
- Gavin Screaton
- Timothy EA Peto
- Bruno Holthof
- Anne-Marie O'Donnell
- Daniel Ebner
- Christopher P Conlon
- Katie Jeffery
- Timothy M Walker
Wellcome Trust Clinical Research Training Fellow (216417/Z/19/Z)
- Ali Amini
NIHR Clinical Lecturer
- Bernadette C Young
Structural Genomics Consortium
- Lucas Martins Ferreira
- Thomas Christott
- Brian D Marsden
Kennedy Trust for Rheumatology Research
- Brian D Marsden
Wellcome Trust Senior Investigator
- Gavin Screaton
Schmidt Foundation
- Gavin Screaton
Wellcome Trust Career Development Fellow (214560/Z/18/Z)
- Timothy M Walker
National Institute of Health Research Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance (HPRU-2012-10041)
- David W Eyre
- Sheila F Lumley
- Denise O'Donnell
- Mark Campbell
- Elizabeth Sims
- Elaine Lawson
- Fiona Warren
- Tim James
- Stuart Cox
- Alison Howarth
- George Doherty
- Stephanie B Hatch
- James Kavanagh
- Kevin K Chau
- Philip W Fowler
- Jeremy Swann
- Denis Volk
- Fan Yang-Turner
- Nicole Stoesser
- Philippa C Matthews
- Maria Dudareva
- Timothy Davies
- Robert H Shaw
- Leon Peto
- Louise O Downs
- Alexander Vogt
- Ali Amini
- Bernadette C Young
- Philip George Drennan
- Alexander J Mentzer
- Donal T Skelly
- Fredrik Karpe
- Matt J Neville
- Monique Andersson
- Andrew J Brent
- Nicola Jones
- Lucas Martins Ferreira
- Thomas Christott
- Brian D Marsden
- Sarah Hoosdally
- Richard Cornall
- Derrick W Crook
- David I Stuart
- Gavin Screaton
- Timothy EA Peto
- Bruno Holthof
- Anne-Marie O'Donnell
- Daniel Ebner
- Christopher P Conlon
- Katie Jeffery
- Timothy M Walker
Robertson Foundation
- David W Eyre
NIHR Oxford BRC Senior Fellow
- David W Eyre
- Philippa C Matthews
Wellcome Trust Clinical Research Fellow
- Sheila F Lumley
Medical Research Council (MR/N00065X/1)
- David I Stuart
Wellcome Trust Intermediate Fellowship (110110/Z/15/Z)
- Philippa C Matthews
NIHR Doctoral Research Fellow
- Maria Dudareva
Medical Research Foundation (MRF-145-004-TPG-AVISO)
- Kevin K Chau
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Marc Lipsitch, Harvard TH Chan School of Public Health, United States
Ethics
Human subjects: All asymptomatic staff data collection and testing were part of enhanced hospital infection prevention and control measures instituted by the UK Department of Health and Social Care (DHSC). Deidentified data from staff testing and patients were obtained from the Infections in Oxfordshire Research Database (IORD) which has generic Research Ethics Committee, Health Research Authority and Confidentiality Advisory Group approvals (19/SC/0403, ECC5-017(A)/2009). De-identified patient data extracted included admission and discharge dates, ward location and positive Covid-19 test results.
Version history
- Received: July 2, 2020
- Accepted: August 18, 2020
- Accepted Manuscript published: August 21, 2020 (version 1)
- Version of Record published: September 11, 2020 (version 2)
Copyright
© 2020, Eyre 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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Differential occupational risks to healthcare workers from SARS-CoV-2 observed during a prospective observational study
eLife 9:e60675.
https://doi.org/10.7554/eLife.60675
Further reading
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- Epidemiology and Global Health
Background:
The Zanzibar archipelago of Tanzania has become a low-transmission area for Plasmodium falciparum. Despite being considered an area of pre-elimination for years, achieving elimination has been difficult, likely due to a combination of imported infections from mainland Tanzania and continued local transmission.
Methods:
To shed light on these sources of transmission, we applied highly multiplexed genotyping utilizing molecular inversion probes to characterize the genetic relatedness of 282 P. falciparum isolates collected across Zanzibar and in Bagamoyo district on the coastal mainland from 2016 to 2018.
Results:
Overall, parasite populations on the coastal mainland and Zanzibar archipelago remain highly related. However, parasite isolates from Zanzibar exhibit population microstructure due to the rapid decay of parasite relatedness over very short distances. This, along with highly related pairs within shehias, suggests ongoing low-level local transmission. We also identified highly related parasites across shehias that reflect human mobility on the main island of Unguja and identified a cluster of highly related parasites, suggestive of an outbreak, in the Micheweni district on Pemba island. Parasites in asymptomatic infections demonstrated higher complexity of infection than those in symptomatic infections, but have similar core genomes.
Conclusions:
Our data support importation as a main source of genetic diversity and contribution to the parasite population in Zanzibar, but they also show local outbreak clusters where targeted interventions are essential to block local transmission. These results highlight the need for preventive measures against imported malaria and enhanced control measures in areas that remain receptive to malaria reemergence due to susceptible hosts and competent vectors.
Funding:
This research was funded by the National Institutes of Health, grants R01AI121558, R01AI137395, R01AI155730, F30AI143172, and K24AI134990. Funding was also contributed from the Swedish Research Council, Erling-Persson Family Foundation, and the Yang Fund. RV acknowledges funding from the MRC Centre for Global Infectious Disease Analysis (reference MR/R015600/1), jointly funded by the UK Medical Research Council (MRC) and the UK Foreign, Commonwealth & Development Office (FCDO), under the MRC/FCDO Concordat agreement and is also part of the EDCTP2 program supported by the European Union. RV also acknowledges funding by Community Jameel.
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- Epidemiology and Global Health
- Microbiology and Infectious Disease
Background: Few national-level studies have evaluated the impact of 'hybrid' immunity (vaccination coupled with recovery from infection) from the Omicron variants of SARS-CoV-2.
Methods: From May 2020 to December 2022, we conducted serial assessments (each of ~4000-9000 adults) examining SARS-CoV-2 antibodies within a mostly representative Canadian cohort drawn from a national online polling platform. Adults, most of whom were vaccinated, reported viral test-confirmed infections and mailed self-collected dried blood spots to a central lab. Samples underwent highly sensitive and specific antibody assays to spike and nucleocapsid protein antigens, the latter triggered only by infection. We estimated cumulative SARS-CoV-2 incidence prior to the Omicron period and during the BA.1/1.1 and BA.2/5 waves. We assessed changes in antibody levels and in age-specific active immunity levels.
Results: Spike levels were higher in infected than in uninfected adults, regardless of vaccination doses. Among adults vaccinated at least thrice and infected more than six months earlier, spike levels fell notably and continuously for the nine months post-vaccination. By contrast, among adults infected within six months, spike levels declined gradually. Declines were similar by sex, age group, and ethnicity. Recent vaccination attenuated declines in spike levels from older infections. In a convenience sample, spike antibody and cellular responses were correlated. Near the end of 2022, about 35% of adults above age 60 had their last vaccine dose more than six months ago, and about 25% remained uninfected. The cumulative incidence of SARS-CoV-2 infection rose from 13% (95% CI 11-14%) before omicron to 78% (76-80%) by December 2022, equating to 25 million infected adults cumulatively. However, the COVID-19 weekly death rate during the BA.2/5 waves was less than half of that during the BA.1/1.1 wave, implying a protective role for hybrid immunity.
Conclusions: Strategies to maintain population-level hybrid immunity require up-to-date vaccination coverage, including among those recovering from infection. Population-based, self-collected dried blood spots are a practicable biological surveillance platform.
Funding: Funding was provided by the COVID-19 Immunity Task Force, Canadian Institutes of Health Research, Pfizer Global Medical Grants, and St. Michael's Hospital Foundation. PJ and ACG are funded by the Canada Research Chairs Program.
