The recent publication of two studies finding no differences between surgical masks and respirators for protecting healthcare workers against respiratory virus transmission has inspired pushback from leading infectious disease experts, who slammed the research conclusions in Thursday commentary.

“These studies are deeply flawed,” wrote Michael Osterholm, PhD, MPH, and colleagues in CIDRAP News, a publication of the Center for Infectious Disease Research & Policy at the University of Minnesota.

The studies in question, published in the Annals of Internal Medicine and in Cochrane Reviews “are built on the premise that infectious respiratory viruses like SARS-CoV, SARS-CoV-2, MERS-CoV and influenza are only transmitted person to person by large droplets. This is not true,” the authors contended.

“The science is very clear that the predominant mode by which these viruses are transmitted person to person is inhalation of small particles,” they explained.

Osterholm and colleagues previously have argued that cloth and surgical masks do not provide significant protection against person-to-person transmission of respiratory disease such as COVID-19 and flu due to variables including filtering ability and fit. 

Respirators, on the other hand, are not technically masks, have effective filters that prevent aerosol inhalation, and are designed to fit most faces, they stated in the new commentary. 

Any type of respirator filter approved by the National Institute for Occupational Safety & Health, such as N, P, R, 95, 99 and 100 “will be effective at collecting human-generated aerosols,” including the small particles associated with respiratory virus transmission, Osterholm and colleagues wrote. “Although designed to protect the wearer from inhaling hazardous aerosols, an N95 filtering facepiece respirator (FFR) will also prevent the outward leakage of particles produced by the wearer when breathing, talking, singing, etc.”

Employers have a responsibility to make sure that their workers are well protected, they added.

“In workplaces, employers must test the fit of a respirator on every employee to ensure they’re getting the required level of protection,” they said.

The full commentary is available on CIDRAP’s website.

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