SUMMARY Since the beginning of the COVID-19 pandemic, there has been intense debate over SARS-CoV-2’s mode of transmission and appropriate personal protective equipment for health care workers in low-risk settings. The objective of this review is to identify and appraise the available evidence (clinical trials and laboratory studies on masks and respirators, epidemiological studies, and air sampling studies), clarify key concepts and necessary conditions for airborne transmission, and shed light on knowledge gaps in the field. We find that, except for aerosol-generating procedures, the overall data in support of airborne transmission—taken in its traditional definition (long-distance and respirable aerosols)—are weak, based predominantly on indirect and experimental rather than clinical or epidemiological evidence. Consequently, we propose a revised and broader definition of “airborne,” going beyond the current droplet and aerosol dichotomy and involving short-range inhalable particles, supported by data targeting the nose as the main viral receptor site. This new model better explains clinical observations, especially in the context of close and prolonged contacts between health care workers and patients, and reconciles seemingly contradictory data in the SARS-CoV-2 literature. The model also carries important implications for personal protective equipment and environmental controls, such as ventilation, in health care settings. However, further studies, especially clinical trials, are needed to complete the picture.

Background Canadian long‐term care facility (LTCF) residents experienced higher death rates compared to other countries during the first wave of the COVID‐19 pandemic. This cohort study analyzes the individual, therapeutic, and institutional factors associated with death in LTCFs. Methods Institutional data for 17 LTCFs in Montreal, Canada were obtained from local administrative registries. Individual data for 1197 residents infected by SARS‐CoV‐2 between February 23 and July 11, 2020 were obtained through chart reviews. A multivariable modified Poisson regression model, which accounted for LTCF clustering, was used to identify resident and facility covariates associated with 30‐day mortality after COVID‐19 diagnosis. Results Severe shortage of licensed practical nurses (RR 2.60 95% CI 1.20–5.61) and medium‐sized facilities compared to smaller‐sized facilities (RR 2.73 95% CI 1.23–6.07) were associated with 30‐day mortality. Later COVID‐19 diagnosis (RR 0.98 95% CI 0.97–0.99 per additional day) was associated with survival. Individual risk factors for death included age (RR 1.33 95% CI 1.23–1.45 per additional 10 years), male sex (RR 1.46 95% CI 1.24–1.71), functional impairment (RR 1.08 95% CI 1.04–1.12 per unit increase of SMAF), as well as a diagnosis of congestive heart failure (RR 1.31 95% CI 1.04–1.66) and neurocognitive disorder (RR 1.31 95% CI 1.01–1.70). Among severe cases, anticoagulation was associated with survival (RR 0.70 95% CI 0.51–0.96). Conclusions This study identified practical nurse shortages and facility size as institutional risk factors for COVID‐19 death. Anticoagulation was associated with survival among severe cases.

No abstract

Citation Zhang XS, Duchaine C. 2021. Erratum for Zhang and Duchaine, "SARS-CoV-2 and health care worker protection in low-risk settings: a review of modes of transmission and a novel airborne model involving inhalable particles." Clin Microbiol Rev 34:e00009-21.