Transmission risk of SARS-CoV-2 to healthcare workers in a primary care hospital setting

Transmission risk of SARS-CoV-2 to healthcare workers in a primary care hospital setting. Spencer EA, Heneghan C.

https://www.cebm.net/study/transmission-risk-of-sars-cov-2-to-healthcare-workers-in-a-primary-care-hospital-setting/

Published on July 23, 2020

Reference Canova V, Lederer Schläpfer H, Piso RJ, Droll A, Fenner L, Hoffmann T, Hoffmann M Transmission risk of SARS-CoV-2 to healthcare workers –observational results of a primary care hospital contact tracing Swiss Med Wkly. 2020;150:w20257 2020
Study type
Country Switzerland
Setting Primary Care
Funding Details No additional funding was received for the conduction of the study
Transmission mode Person to person, Close contact
Exposures Primary care healthcare

Bottom Line

This study of exposure to an index case in a primary care hospital found a low risk of SARS-CoV-2 transmission. It suggests that routine short clinical examinations and short physical contacts did not facilitate transmission.

Evidence Summary

The index case was a 75-year-old man, admitted to a primary care hospital with angina pectoris and mild respiratory symptoms. 21 healthcare workers reported unprotected contact with the index case attending primary care hospital services.  All 21 were unaware of the index case’s COVID-19 status at the time of contact and none were adhering to the Swissnoso guidelines for personal protective equipment.

All 21 healthcare workers tested SARS-CoV-2 negative 7 days after initial index case contact, 

Three reported respiratory symptoms (cough) or low-grade fever within four days and tested negative for SARS-CoV-2.  Ten reported a cumulative exposure time of >15 minutes. Longer cumulative contact times were associated with more individual contacts, reduced contact time per contact and activities with physical patient contact. 

The closest relative (partner) of the index patient tested SARS-CoV-2 positive two days after the index case presented at the hospital emergency department.

What did they do?

An initially undiagnosed COVID-19 case had contact with a number of healthcare workers after attending a primary care hospital. These healthcare workers did not use personal protective equipment during exposure. 

All healthcare workers filled in a standard questionnaire used for unintentional exposures to pathogens transmitted by droplets or aerosols, according to local standard operating procedures, which evaluated their exposure risk by occupation, location of exposure, approximate cumulative exposure time, number of individual contacts during exposure and activities performed during exposure

Nasopharyngeal swabs were taken when healthcare workers reported respiratory symptoms or fever, and for all healthcare workers 7 days after the initial contact.

Study reliability

It is possible that the index case and his partner contracted the infection from a common source, instead of the index case transmitting it to his partner. Alternatively, the index case may have transmitted the virus in the pre-symptomatic phase.

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

What else should I consider?

About the authors

Carl Heneghan

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

Elizabeth Spencer

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