Healthcare-associated COVID-19 outbreaks: a nationwide population-based cohort study.

Background: Healthcare-associated coronavirus disease 2019 (COVID-19) has significant implications for patients, their companions and healthcare workers (HCWs). Controlling transmission in healthcare settings is critical to reduce deaths due to COVID-19.
Aim: To describe the epidemiology and characteristics of healthcare-associated COVID-19 outbreaks and outbreak-related cases.
Methods: The investigation data for each healthcare-associated outbreak that occurred between 15 ^th January 2020 and 31 ^st July 2021 in Taiwan were analysed retrospectively. Confirmed outbreak-associated cases were categorized as HCW cases, patient companion cases or patient cases, and the characteristics of the confirmed cases were compared between these categories.
Findings: In total, 54 healthcare-associated COVID-19 outbreaks including 512 confirmed cases were reported. The median number of affected cases per outbreak was six [interquartile range (IQR) 2-12], and the median outbreak duration was 12 days (IQR 4.3-17.0). Only 5.7% and 0.2% of all confirmed cases were partially and fully vaccinated, respectively. Most outbreaks (90%, 48/54) occurred in May and June 2021. HCW cases, companion cases and patient cases accounted for 19.5%, 41.2% and 39.3% of the total cases. Patient cases were significantly older (median age 72 years, IQR 61-83) and had higher 30-day all-cause mortality (37.4%) than HCW cases (median age 41 years, IQR 28-58, 0%) and companion cases (median age 52 years; IQR 42-62, 1%).
Conclusion: Healthcare-associated COVID-19 outbreaks have a critical impact on patients. Nevertheless, two-thirds of cases in the healthcare-associated outbreaks in this study comprised HCWs and companions. In order to effectively mitigate COVID-19 transmission in healthcare settings, multi-pronged infection prevention and control measures should be implemented and tailored for these three groups.
(Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)