COVID-19: Differential occupational risks to healthcare workers from SARS-CoV-2

COVID-19: Differential occupational risks to healthcare workers from SARS-CoV-2. Spencer EA, Heneghan C.

Published on July 13, 2020

Reference Eyre DW, Lumley SF, O'Donnell D et al. Differential occupational risks to healthcare workers from SARS-CoV-2: A prospective observational study. medRxiv 2020.06.24.20135038 2020
Study type
Country UK
Setting Hospital
Funding Details UK Government's Department of Health and Social Care; the National Institute for Health Research Health Protection Research Unit in partnership with Public Health England (PHE) [grant HPRU-2012-10041] and the NIHR Biomedical Research Centre, Oxford.
Transmission mode Person to person, Close contact
Exposures Hospitals, Households

Bottom Line

Among 9,809 healthcare employees in a UK hospital in the south-east, an increased risk of COVID-19 was found in staff in acute medicine, among Black and Asian staff, and porters and cleaners. Protective interventions including PPE appeared to reduce risk among intensive care staff.

Evidence Summary

1,083/9,809 (11%) staff had evidence of COVID-19 at some time and provided data on potential risk factors. 

Staff with a confirmed household contact were at greatest risk: adjusted OR 4.63 (95%CI 3.30 to 6.50). 

Higher rates of COVID-19 were found in staff working in COVID-19-facing areas 21.2% vs. 8.2% elsewhere: adjusted OR 2.49 (95%CI 2.00 to 3.12). 

Controlling for COVID-19-facing status, risks varied across the hospital, with higher rates in acute medicine: OR 1.50 (95%CI 1.05 to 2.15) and sporadic outbreaks in areas with few or no COVID-19 patients. 

COVID-19 intensive care unit staff were relatively protected: OR 0.46, 95%CI 0.29 to 0.72. Positive results were more likely in Black (OR 1.61, 95%CI 1.20 to 2.16) and Asian (OR 1.58, 95%CI 1.34 to 1.86]) staff, independent of role or working location, and in porters and cleaners (OR 1.93, 95%CI 1.25 to 2.97). 

Contact tracing around asymptomatic staff did not lead to enhanced case identification.

24% of cases remained PCR-positive at ≥6 weeks post-diagnosis.


What did they do?

Beginning 23rd April 2020, a voluntary COVID-19 testing programme for symptomatic and asymptomatic staff at a UK teaching hospital was performed, using nasopharyngeal PCR testing and immunoassays for IgG antibodies. Up until 8th June 2020, 9,809 staff were tested at least once. 

A positive result by either modality determined a composite outcome. Risk-factors for COVID-19 were investigated using multivariable logistic regression. These included being in the same household as a case; job role; working in a “COVID-19 facing” role; different locations within the hospital.

Study reliability

This is a large well-conducted study. However, it is cross-sectional, it is in a specific hospital setting, and it is possible that recall of some exposures may be biased i.e. affected by the participant’s COVID-19 status.

Clearly defined setting Demographic characteristics described Follow-up length was sufficient Transmission outcomes assessed Main biases are taken into consideration
Yes Yes Yes Yes Yes

What else should I consider?

As with other studies, it is not possible to know what number of study participants had been infected but showed no detectable antibody response at the time of testing.

About the authors

Carl Heneghan

Carl is Professor of EBM & Director of CEBM at the University of Oxford. He is also a GP and tweets @carlheneghan. He has an active interest in discovering the truth behind health research findings

Elizabeth Spencer

Dr Elizabeth Spencer; MMedSci, PhD. Epidemiologist, Nuffield Department for Primary Care Health Sciences, University of Oxford.