SARS-CoV-2 infection in health care workers

SARS-CoV-2 infection in health care workers. Spencer EA, Heneghan C.

Published on June 27, 2020

Reference Yansen Bai Sr., Xuan Wang Sr., Qimin Huang Sr et al. SARS-CoV-2 infection in health care workers: a retrospective analysis and a model study. medRxiv 2020.03.29.20047159; doi:
Study type
Country China
Setting Hospital
Funding Details Non Reported
Transmission mode Person to person, Fomite
Exposures Health Care, Person to person, fomite

Bottom Line

Among 12 Health care workers diagnosed with COVID-19 asked to recall their working patterns pre-outbreak, poor sleep quality and high working pressure were positively associated with higher risks of COVID-19 diagnosis.

Evidence Summary

A higher proportion of COVID-19 health care workers (HCWs) than non-infected had engaged in night shift-work (75% vs. 41%) and felt they were working under pressure (67% vs. 32%). 

All HCW cases had contact with the index case, 28% of the uninfected had contact. Poor sleep quality and high working pressure were positively associated with higher risks of COVID-19 diagnosis.

What did they do?

This study investigated risk factors for COVID-19 infection among 118 health care workers at a single hospital. Among these, 12 were diagnosed with COVID-19. 

A hospitalized patient admitted on 25th December 2019 who was later diagnosed with COVID-19 (and subsequently died on 3rd February) was defined as the index case for these HCW cases. 

171 HCWs were asked to retrospectively report on potential risk factors pertaining to the time prior to the COVID-19 outbreak. Sleep quality and working pressure were evaluated by the Pittsburgh Sleep Quality Index (PSQI) and The Nurse Stress Index (NSI), respectively. 

An online electronic questionnaire was sent to all 171 HCWs in the Department of Neurosurgery of Union Hospital of Wuhan. 

Valid questionnaires from 118 HCWs (69% of the 171 requested) were available for analysis, including questionnaires from 12 COVID-19 HCWs, and 106 uninfected HCWs. 

Data were collected on: age, gender, height, weight, education level, physical activity, smoking status, alcohol drinking status, diet, medical past, and chronic medical diseases. The contact status with COVID-19 case-patients was also collected.

They estimated the basic reproduction number R0, (defined as the average number of secondary infections that arise from a typical primary case in a completely susceptible population).

Follow-up duration was from 25th December 2019 to 15th February 2020. 

Risk factors and transmission models of COVID-19 among HCWs were analyzed and constructed.

Study reliability

Data on risk factors were retrospectively collected and likely to be biased by subsequent disease diagnoses. This was a very small study sample so reliability is low. 

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

What else should I consider?

If there is indeed an increased risk among night shift workers, this could be due to lowered care/protection standards and/or reduced staffing to ensure full safety. A physiological explanation is not necessary.

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.