Masking for COVID-19 tied to fewer ED visits for other respiratory illnesses

The COVID-19 pandemic has forced people to wear mask to prevent the spread of the disease, but the increasing prevalence of masking has also resulted in a reduction in emergency department (ED) visits for other viral illnesses and exacerbations of asthma and chronic obstructive pulmonary disease (COPD), according to a US study.

“These findings may be valuable for future public health responses, particularly in future pandemics with respiratory transmission or in severe influenza seasons,” the researchers said.

This observational study of ED encounters was conducted in a 11-hospital system in Maryland, US, during 2019–2020. The researchers calculated year-on-year ratios for all complaints to account for “lockdowns” and the global drop in ED visits due to the pandemic.

Encounters for specific complaints were identified using the International Classification of Diseases, version 10, but those with a positive COVID test were excluded. The association of publicly available masking data with ED visits for non-COVID viral illnesses (NCVIs) and exacerbations of asthma and COPD was assessed using linear regression, with adjustments for patient age, sex, and medical history.

In 2019 and 2020, ED visits across the hospital system had a total of 285,967 and 252,598, respectively. A trend toward an association between the year-on-year ratio for all ED visits and the Maryland stay-at-home order (parameter estimate, –0.0804; p=0.10) was noted. [Am J Med 2021;134:1247-1251]

A 10-percent increase in the prevalence of community masking led to a decrease in ED visits for NCVI (17.0 percent) and exacerbations of asthma (8.8 percent) and COPD (9.4 percent; p<0.001 for all).

“Masking had not been widely adopted in the US until the COVID pandemic, making it difficult to investigate how masking in the community could impact ED visits,” the researchers said. [N Engl J Med 2010;362:e65]

“The majority of Maryland citizens wore masks during the COVID-19 pandemic, and masks block a variety of respiratory viruses, providing a natural experiment to determine the effects of general masking on ED visits,” they added. [Lancet 2020;395:1973-1987; https://covid19.healthdata.org/]

The overall drop in ED visits during the pandemic observed in the current study was also noted by other investigators. [MMWR Morb Mortal Wkly Rep 2020;69:699-704; Hosp Pediatr 2021;11:e57-e60]

“These findings suggest the well-known decrease in person-to-person transmission of respiratory viruses due to masking also has a measurable and positive impact on health systems,” the researchers said. “These results also suggest there is a public health benefit to community masking after the COVID-19 pandemic.” [Lancet 2020;395:1973-1987]

Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Disease, echoed these outcomes, saying that “[w]e’ve had practically a nonexistent flu season this year merely because people were doing the kinds of public health things that were directed predominantly against COVID-19.” [https://www.washingtonpost.com/health/2021/05/09/fauci-covid-masks-seasonal-pandemic/]

The researchers, however, noted that “the 2020 influenza season may have been mild regardless of the COVID-19 pandemic, which would serve to overestimate the impact of masking in this analysis.”

“Some patients that would have had NCVI instead may have died from COVID-19 instead, effectively depressing the severity of the 2020 influenza season and the impact of masking in this analysis,” they added.