Healthcare workers experience significant burdens from coronavirus infections, including severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), according to a review study published in the Annals of Internal Medicine

In order to investigate the burden of SARS-CoV-2, SARS-CoV-1, and Middle Eastern respiratory syndrome (MERS)-CoV on healthcare workers and potential risk factors for infection, investigators abstracted data and assessed methodologic limitations from published studies.

Databases including the World Health Organization Database of Publications on Coronavirus Disease, the medRxiv preprint server (2003 through March 27, 2020, with ongoing surveillance through April 24, 2020), and reference lists were screened. Published work in any language that reported on incidence of or outcomes associated with coronavirus infections in healthcare workers as well as those investigating the association between risk factors (demographic characteristics, role, exposures, environmental and administrative factors, and personal protective equipment use) and infections were included.

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In total, 64 studies met criteria for inclusion in the review; 43 studies addressed healthcare worker infections and 34 addressed risk factors. Among studies concerned with infections or risk factors, 15 and 3 studies, respectively, were on SARS-CoV-2, specifically. Healthcare workers accounted for a significant percentage of infections and the literature highlighted that that may experience particularly high infection incidence after unprotected exposures. Illness severity was however lower than among non-healthcare workers. Among healthcare workers, depression, anxiety, and psychological distress were common during the coronavirus disease 2019 outbreak.

One study reported, in regards to SARS-CoV-2, that healthcare workers accounted for 3.8% (1716 cases) of 44,672 confirmed cases of COVID-19 diagnosed in China through February 11, 2020. The percentage of healthcare workers cases classified as severe or critical was 15%, and the case-fatality rate was 0.3%. Another study noted that healthcare workers accounted for 5.1% (1316 of 25,961) of cases and the overall estimated incidence was higher among healthcare workers than the general population.

In terms of SARS-CoV-1, the prevalence of seropositivity in exposed or potentially exposed healthcare workers ranged from 0.3% to 40% across 6 studies and SARS-CoV-1 incidence ranged from 1.2% to 29.4% in 14 studies.

Literature on MERS-CoV demonstrated that of the 651 MERS cases diagnosed worldwide between July to December, 14% to 18% occurred in healthcare workers in 2014 and 2015 and 0 to 4% in 2018 and 2019. An analysis of all cases of MERS in healthcare workers reported to the World Health Organization showed an overall case-fatality rate of 5.8%.

In terms of risk factors, the strongest evidence linked the use of personal protective equipment and decreased risk of developing infection. This association was most consistent for the use of masks, but also observable for gloves, gowns, eye protection and hand washing. Some specific exposures were associated with increased infection risk, such as longer work hours, working in a high-risk department, involvement in intubations, direct patient contact, or contact with bodily secretions, whereas infection control training was associated with decreased risk.

According to investigators, this work was limited in that, “there were few studies on risk factors for SARS-CoV-2, the studies had methodological limitations, and streamlined rapid review methods were used.”

Investigators concluded that more studies are needed to better understand the percentage of exposed healthcare workers who are infected with SARS-CoV-2 and associated outcomes. These include, economic effects, ability to work, social effects and effects on family members and other close contacts, including transmission. Studies evaluating mental health and other outcomes should also control for baseline status, include non-healthcare worker controls and use longitudinal follow-up. For infection risk factors, “studies that prospectively measure exposures, [personal protective equipment] use, and other factors would increase measurement accuracy, reduce recall bias, and enable analyses that minimize confounding.” Finally, multivariate analyses of risk factors should account for potential collinearity and effects on personal protective equipment reuse are urgently needed as are those on the association between administrative and environmental factors, and healthcare worker health and infection risk.

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Chou R, Dana T, Buckley DI, Selph S, Fu R, Totten AM. Epidemiology of and risk factors for coronavirus infection in health care workers [published online May 5 2020]. Ann Intern Med. doi:10.7326/M20-1632