Medical masks comparable to N95 respirators for preventing COVID-19?

A study of more than 1,000 health care workers was unable to establish whether medical masks are significantly less effective at preventing COVID-19 infection than N95 respirators in hospital settings. The findings varied across countries, which were studied during different times in the pandemic. The study is published in Annals of Internal Medicine. Either medical masks or N95 respirators are recommended by the World Health Organization for routine care, whereas only N95 respirators are recommended by the Centers for Disease Control and Prevention for the routine care of patients with COVID-19. It is uncertain if medical masks offer similar protection against COVID-19 compared with N95 respirators.

Participants were randomly assigned to universal masking with either a medical mask or a fit-tested N95respirator for 10 weeks. The primary outcome was confirmed COVID-19 on the RT-PCR test. The authors found that confirmed COVID-19 occurred in 10.46 percent of the medical mask group versus 9.27 percent in the N95 respirator group.

However, the results varied by country. This may have been due to differences in vaccine use, the number of people with previous infection, and the type of variant circulating in the study countries which were enrolled during different times in the pandemic.

The authors indicate that medical masks were found to be not significantly less effective than N95 respirators.

Decisions about mask types in health care workers should be informed by the uncertainty around the estimates and continue to account for health care worker preferences about potential trade-offs, N95 respirator availability, and resource constraints.

Reference:

In some settings, medical masks may offer similar effectiveness to N95 respirators for preventing COVID-19 infection among health care workers; Annals of Internal Medicine, DOI: 10.7326/M22-1966