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August 12, 2023
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Clinicians should consider masking during elevated respiratory viral activity, experts say

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Key takeaways:

  • Rates of non-SARS-CoV-2 viral respiratory infections were lowest during 2020/2021.
  • The intra-pandemic period when preventative measures began was linked with a 100% decrease in hospital-onset influenza and RSV.

Experts said clinicians should consider masking during periods of elevated respiratory viral activity after a study linked pandemic prevention measures to decreases in nosocomial COVID-19 and other respiratory viruses.

“Our study was prompted by our curiosity [about] whether the interventions we put in place to decrease transmission of SARS-CoV-2 in the hospital also helped decrease hospital-acquired infections due to other respiratory viruses like influenza and [respiratory syncytial virus],” Michael Klompas MD, MPH, FIDSA, FSHEA, hospital epidemiologist at Brigham and Women’s Hospital and professor of medicine and population medicine at Harvard Medical School and Harvard Pilgrim Health Care Institute, told Healio.

Surgical_Masks 1
Incidence in non-SARS-CoV-2 respiratory infection incidence rates decreased 44% to 53% after infection control measures to prevent SARS-CoV-2 were implemented, suggesting the potential benefit of masking on transmission. Image: Adobe Stock.

Klompas and colleagues used data from Brigham and Woman’s Hospital to assess monthly counts of patients with incident positive influenza, parainfluenza, adenovirus, human metapneumovirus (HMPV), rhinovirus and RSV PCR or antigen tests between October 2015 and April 2023.

All cases were then categorized as community onset if detected on hospital days 1 to 3 and hospital onset if first detected on hospital day 4 or later. According to the study, the researchers then calculated the monthly frequency of hospital-onset respiratory viral infection per 1,000 admissions and used an interrupted time-series analysis to assess for changes in the incidence of hospital-onset respiratory viral infections after the implementation of infection control measures to reduce in-hospital transmission of SARS-CoV-2 starting in March 2020.

These control measures included universal masking of patients and providers, requiring employees to attest to lack of respiratory viral symptoms before each shift, visitor restrictions and regularly screening patients for new respiratory viral symptoms.

Results were then divided into three periods: pre-pandemic (October 2015 to March 2020); the intra-pandemic period, during which the community incidence of influenza and RSV was near zero (April 2020 to August 2021); and the post-acute-pandemic period, during which the community incidence of influenza and RSV rose again (September 2021 to April 2023).

Across all 8 years, the team detected 436 hospital-onset respiratory viral infections, most of which occurred during the fall and winter months of October to March (72.2%). These infections were primarily influenza (28.4%), RSV (19.3%) and rhinovirus (26.1%), although the researchers found that HMPV (9.2%), parainfluenza (11.9%) and adenovirus (5%) were also detected.

According to the study, incidence rates were highest in winter 2019/2020 (4 cases per 1,000 admissions) and lowest in 2020/2021 (0.55 cases per 1,000 admissions). Additionally, on average, 14.9% of all respiratory viral infections among hospitalized patients during respiratory viral seasons (October to March) were hospital onset, ranging from 9.8% in 2015/2016 to 20.9% in 2018/2019 and 20.2% in 2019/2020.

The study also revealed that the intra-pandemic period was associated with a 100% decrease in hospital-onset influenza and RSV compared with the pre-pandemic period. The post-acute-pandemic period was associated with a 53% decrease in hospital-onset influenza and RSV compared with the pre-pandemic period when using influenza-like illness rates to adjust for community incidence (RR = 0.47; 95% CI, 0.14-0.62) and a 44% decrease in hospital-onset influenza and RSV vs. the pre-pandemic period when using community-acquired influenza and RSV hospitalizations to adjust for community incidence (RR = 0.56; 95% CI, 0.14-0.74).

These findings, which overall showed a 44% to 53% decrease in non-SARS-CoV-2 virus incidence after infection control measures were implemented, suggest the potential impact of masking on respiratory viral infections transmission.

Health care organizations and individual clinicians should strongly consider masking themselves during periods when respiratory viral activity is elevated in order to protect patients from health care-associated respiratory viral infections,” Klompas concluded.