N-95 or Plain Mask to Prevent Flu?

Written by Clay Smith

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There was no difference between a regular medical mask and N-95 mask worn by healthcare workers in preventing influenza or any other respiratory infection.

Why does this matter?
Healthcare personnel worry about catching infection from patients. Many wear masks for protection. Some wear the more uncomfortable, but presumably more efficacious N-95 masks, that protect from not only droplets but smaller airborne droplet nuclei, such as TB at 1-5 microns. Does it make a difference which mask is used?

This ID Week abstract is important
I ran across this on the HIV and ID Observations Blog. It was an oral abstract at ID Week so is not yet peer reviewed. But here goes. Is a plain medical mask (MM) or N-95 mask better in avoiding transmission of viral respiratory pathogens to healthcare workers (HCW)? This was a cluster randomized trial of HCW who wore either a regular MM or N-95 mask when working within 6 feet of a patient with suspected viral respiratory illness. This was done over several seasons and enrolled 2,243 to wear N95 masks and 2,446 to MM. Rates of influenza were confirmed in HCW by PCR and hemagglutinin inhibition assays; secondary outcomes were, “acute respiratory illness (ARI), influenza like illness (ILI), laboratory-confirmed respiratory illness (LCRI), and laboratory detected respiratory infection (LDRI).” They found no statistically significant difference between masks in rate of influenza or any other respiratory infection. About 7% got the flu with the MM; about 8% with the N-95. A lot of HCW got some kind of acute respiratory illness, 62-64%, with no difference between masks. Bottom line is a regular mask is just as good at protecting from common wintertime viruses and influenza as the N-95.

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