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One of the most concerning aspects of COVID-19 is the risk for infection among frontline healthcare workers (HCWs). Now, two new studies provide further insights into the epidemiology of COVID-19 in HCWs.
During a 1-week period in late April, 2020, investigators offered serologic testing to all asymptomatic HCWs working in a Belgian tertiary-care hospital where care had been provided to COVID-19 patients since March 13 and filtering facepiece respirators had been provided as personal protective equipment (PPE) to HCWs since April 3.
Serologic testing was performed on 3056 members (74%) of the hospital staff, of which 197 (6.4%) were found to have immunoglobulin G (IgG) antibodies to the SARS-CoV-2 nucleocapsid protein. HCWs with household exposure to COVID-19 were more likely to be antibody-positive than those without household exposure. However, HCWs with exposure to patients, SARS-CoV-2–positive patients, or SARS-CoV-2–positive HCW coworkers were not more likely to be antibody-positive than those without such exposures. The majority of antibody-positive HCWs (75%) remembered having one or more symptoms prior to testing, most commonly anosmia, fever, and cough.
In a separate study, conducted during a 3-week period in April 2020, investigators used a SARS-CoV-2 real-time reverse transcription polymerase chain reaction assay to screen asymptomatic and symptomatic HCWs in a large U.K. teaching hospital as well as symptomatic HCW household contacts. Routine PPE included surgical scrubs and surgical masks, except during aerosol-generating procedures, when additional equipment was used.
Of 1032 asymptomatic HCWs, 3% tested positive for SARS-CoV-2, and of 169 symptomatic HCWs and 52 household contacts, 14% tested positive. HCWs that worked on wards providing care for patients with confirmed or suspected COVID-19 were more likely to test positive than were HCWs working on other wards. Two clusters of asymptomatic SARS-CoV-2–positive HCWs were identified: Viral genomic analysis found that six of nine SARS-CoV-2–positive HCWs on a unit for non–COVID-19 patients had related viral isolates, as did all four SARS-CoV-2–positive HCWs (for whom sequence data were available) on a unit for confirmed COVID-19 patients.
Steensels D et al. Hospital-wide SARS-CoV-2 antibody screening in 3056 staff in a tertiary center in Belgium. JAMA 2020 Jun 15; [e-pub]. (https://doi.org/10.1001/jama.2020.11160)
Rivett L et al. Screening of healthcare workers for SARS-CoV-2 highlights the role of asymptomatic carriage in COVID-19 transmission. eLife 2020 May 11; 9:e58728. (https://doi.org/10.7554/eLife.58728)
Comment
These two reports provide perspective on the complex epidemiology of COVID-19 in HCWs. The different rates of HCW infection on COVID-19 units in the two studies suggest that use of a higher level of PPE may be beneficial. Acquisition of the virus in the community is clearly important, but the finding of a cluster of infected HCWs with related virus who were working on a non–COVID-19 ward also raises the concern of potential HCW-to-HCW transmission. The findings of both studies also suggest that routine screening of HCWs is likely necessary to afford maximal protection to both this at-risk population and hospitalized patients.