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