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Serologic Surveillance and Phylogenetic Analysis of SARS-CoV-2 Infection Among Hospital Health Care Workers

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To identify the key insights or developments described in this article
1 Credit CME
Key Points

Question  Which hospital health care workers are at increased risk for SARS-CoV-2 infection, and by whom are they infected?

Findings  In this cohort study of 801 hospital health care workers (HCWs), the risk of getting infected with SARS-CoV-2 was nearly 4-fold higher among HCWs on COVID-19 wards compared with HCWs not in patient care. Combined phylogenetic and epidemiological analyses found no patient-to-HCW transmission but several occurrences of HCW-to-HCW transmission.

Meaning  These findings suggest that transmission of SARS-CoV-2 between HCWs deserves more consideration in infection prevention practice.

Abstract

Importance  It is unclear when, where, and by whom health care workers (HCWs) working in hospitals are infected with SARS-CoV-2.

Objective  To determine how often and in what manner nosocomial SARS-CoV-2 infection occurs in HCW groups with varying exposure to patients with COVID-19.

Design, Setting, and Participants  This cohort study comprised 4 weekly measurements of SARS-CoV-2–specific antibodies and collection of questionnaires from March 23 to June 25, 2020, combined with phylogenetic and epidemiologic transmission analyses at 2 university hospitals in the Netherlands. Included individuals were HCWs working in patient care for those with COVID-19, HCWs working in patient care for those without COVID-19, and HCWs not working in patient care. Data were analyzed from August through December 2020.

Exposures  Varying work-related exposure to patients infected with SARS-CoV-2.

Main Outcomes and Measures  The cumulative incidence of and time to SARS-CoV-2 infection, defined as the presence of SARS-CoV-2–specific antibodies in blood samples, were measured.

Results  Among 801 HCWs, there were 439 HCWs working in patient care for those with COVID-19, 164 HCWs working in patient care for those without COVID-19, and 198 HCWs not working in patient care. There were 580 (72.4%) women, and the median (interquartile range) age was 36 (29-50) years. The incidence of SARS-CoV-2 was increased among HCWs working in patient care for those with COVID-19 (54 HCWs [13.2%; 95% CI, 9.9%-16.4%]) compared with HCWs working in patient care for those without COVID-19 (11 HCWs [6.7%; 95% CI, 2.8%-10.5%]; hazard ratio [HR], 2.25; 95% CI, 1.17-4.30) and HCWs not working in patient care (7 HCWs [3.6%; 95% CI, 0.9%-6.1%]; HR, 3.92; 95% CI, 1.79-8.62). Among HCWs caring for patients with COVID-19, SARS-CoV-2 cumulative incidence was increased among HCWs working on COVID-19 wards (32 of 134 HCWs [25.7%; 95% CI, 17.6%-33.1%]) compared with HCWs working on intensive care units (13 of 186 HCWs [7.1%; 95% CI, 3.3%-10.7%]; HR, 3.64; 95% CI, 1.91-6.94), and HCWs working in emergency departments (7 of 102 HCWs [8.0%; 95% CI, 2.5%-13.1%]; HR, 3.29; 95% CI, 1.52-7.14). Epidemiologic data combined with phylogenetic analyses on COVID-19 wards identified 3 potential HCW-to-HCW transmission clusters. No patient-to-HCW transmission clusters could be identified in transmission analyses.

Conclusions and Relevance  This study found that HCWs working on COVID-19 wards were at increased risk for nosocomial SARS-CoV-2 infection with an important role for HCW-to-HCW transmission. These findings suggest that infection among HCWs deserves more consideration in infection prevention practice.

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Article Information

Accepted for Publication: May 7, 2021.

Published: July 28, 2021. doi:10.1001/jamanetworkopen.2021.18554

Open Access: This is an open access article distributed under the terms of the CC-BY License. © 2021 Sikkens JJ et al. JAMA Network Open.

Corresponding Author: Jonne J. Sikkens, MD, PhD, Department of Internal Medicine, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, Vrije Universiteit Amsterdam, De Boelelaan 1117, 1081HV, Noord Holland, the Netherlands (j.sikkens@amsterdamumc.nl).

Author Contributions: Drs Sikkens and Bomers had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.

Concept and design: Sikkens, Buis, Peters, Dekker, Schuurman, Russell, Wiersinga, Smulders, de Jong, Bomers.

Acquisition, analysis, or interpretation of data: All authors.

Drafting of the manuscript: Sikkens, Maas, Koopsen, Han, Jonges, Bomers.

Critical revision of the manuscript for important intellectual content: Sikkens, Buis, Peters, Dekker, M. Schinkel, Reijnders, Schuurman, Brabander, Lavell, Koopsen, Han, Russell, J. Schinkel, Matamoros, Jurriaans, Mansfeld, Wiersinga, Smulders, de Jong, Bomers.

Statistical analysis: Sikkens, Buis, Reijnders, Koopsen, Han, Russell, J. Schinkel, Jonges, Matamoros, Smulders, Bomers.

Obtained funding: Sikkens, Wiersinga, Smulders, Bomers.

Administrative, technical, or material support: Sikkens, Buis, Peters, Dekker, M. Schinkel, Reijnders, Schuurman, Brabander, Lavell, Maas, Jonges, Matamoros, Jurriaans, Bomers.

Supervision: Sikkens, Peters, Russell, Wiersinga, Smulders, de Jong, Bomers.

Conflict of Interest Disclosures: Drs Sikkens, Peters, Dekker, Wiersinga, Smulders, and Bomers reported receiving grants from the Netherlands Organisation for Health Research and Development during the conduct of the study. Dr de Jong reported receiving fees paid to the Amsterdam University Medical Centers from Roche, Vertex, Janssen, and Cidara outside the submitted work. No other disclosures were reported.

Funding/Support: This study was funded by a grant from the Netherlands Organization for Health Research and Development and the Amsterdam University Medical Centers Corona Research Fund.

Role of the Funder/Sponsor: The funders had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication.

Additional Contributions: Adinda Pijpers, BSc; Esmee Das, BSc; Nikita Borstlap, BSc; and Lisa Urlings, BSc (all Amsterdam University Medical Centers Faculty of Medicine) helped in performing the study measurements. These contributors received salary payments for some but not all of their efforts.

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