from the editor
Beating the Hornet ’ s Nest : The Challenge of Noninferiority of Respiratory Protection
The news that a study of more than 1,000 healthcare workers was unable to establish whether medical masks are significantly less effective at preventing COVID-19 infection than N95 respirators in hospital settings , seems to have stirred up the social media world with its findings and observations . The authors do note , however , that the findings varied across countries — which were studied during different times in the pandemic — and acknowledged uncertainty in the estimates of effect limit definitiveness of findings . The good news is that it was a randomized controlled trial , something we don ’ t see enough of in the medical literature in our segment .
To review , either medical masks or N95 respirators are recommended by the World Health Organization ( WHO ) for routine care , whereas only N95 respirators are recommended by the Centers for Disease Control and Prevention ( CDC ) for the routine care of COVID-19 patients . The authors say it is uncertain if medical masks offer similar protection against COVID-19 compared with N95 respirators .
The researchers from McMaster University studied 1,009 healthcare workers who provided direct care to patients with suspected or confirmed COVID-19 in 29 inpatient or long-term care settings in Canada , Israel , Pakistan , and Egypt . Participants were randomly assigned to universal masking with either a medical mask or a fit-tested N95 respirator for 10 weeks . The primary outcome was confirmed COVID-19 on reverse transcriptase polymerase chain reaction ( 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 , which ruled out a doubling in hazard of RT-PCR – confirmed COVID-19 . However , the results varied by country : 6.11 percent versus 2.22 percent in Canada ; 35.29 percent versus 23.53 percent in Israel ; 3.26 percent versus 2.13 percent in Pakistan ; and 13.62 percent versus 14.56 percent in Egypt . The researchers say 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 while medical masks were found to be not significantly less effective than N95 respirators , and the efficacy estimate was within the noninferiority margin of 2 , this margin was wide , and between-country heterogeneity in an unplanned analysis may limit definitive conclusions about noninferiority .
In an accompanying editorial , Roger Chou , MD , of Oregon Health & Science University , says that this trial provides the best evidence to date on comparative effectiveness of mask types in preventing COVID-19 infection in healthcare workers providing routine patient care . The results indicate that medical masks may be similar to N95 respirators in Omicron-era settings with high COVID-19 seroprevalence but would not have met a more stringent noninferiority threshold . Chou notes that decisions about mask types in healthcare workers should be informed by the uncertainty around the estimates and continue to account for healthcare worker preferences about potential trade-offs , N95 respirator availability , and resource constraints .
As we know , that can be challenging due to persistent supply chain challenges and the specter of more PPE shortages , as well as group purchasing organizations ’ restrictive contracts and other mitigating factors . Noninferiority in PPE remains one of those unresolved issues , at least for now .
Until next month , bust those bugs ! Kelly M . Pyrek Editor & Publisher kelly @ healthcarehygienemagazine . com
Reference : Loeb M , et al . Medical Masks Versus N95 Respirators for Preventing COVID-19 Among Health Care Workers : A Randomized Trial . Ann Intern Med . Nov . 29 , 2022 . https :// doi . org / 10.7326 / M22-1966 healthcarehygienemagazine
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