Impact of universal masking in reducing the risk of nosocomial respiratory viruses among people with cancer.

Background: Universal masking within healthcare settings was adopted to combat the spread of coronavirus disease 2019 (COVID-19). In addition to mitigating the risk for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection, it also had an added benefit of preventing the nosocomial transmission of other respiratory viral diseases.

Objective: This study examines the impact of the masking intervention on nosocomial respiratory viral infections (RVI) in vulnerable sub-populations of people with cancer at a tertiary care hospital.

Design: Interrupted time series analysis.

Methods: We reviewed non-SARS-CoV-2 nosocomial RVI between January 1, 2017 and December 31, 2023 and compared its quarterly trends before (January 2017 to March 2020) and after (April 2020 to December 2023) the universal masking intervention was implemented.

Results: Prior to the masking policy, there was no significant change in the quarterly rate of non-SARS-CoV-2 nosocomial RVI (baseline trend: P = 0.662). Crude infection rates decreased from 5.6% preintervention to 4.3% after the masking policy was implemented (P < 0.001). Quarterly trends continued to steadily decline post-intervention (β = -0.10, SE = 0.04, P < 0.007).

Conclusions: Our results suggest that universal face masking is associated with reduced non-SARS-CoV-2 nosocomial RVI, providing further evidence to support the continued use of face masks in healthcare settings to protect the health of immunocompromised patients.