Surgical Masks vs N95 Respirators for Preventing Influenza—Reply

In Reply: Drs Palen and Felix ask about the frequency and auditing of changing respiratory devices. Surgical masks and N95 respirators were used once for each encounter with a febrile respiratory patient; the auditor did not collect data on frequency of device changing. Dr Bitar raises the issue of differing filtering capabilities among surgical masks. Because of the variety of surgical masks used at the various institutions and the lack of epidemiological evidence showing differences in influenza event rates by type of surgical mask, we did not take this into consideration when conducting the trial. Each institution used the surgical mask it had in place, including classic surgical masks (Kimberly-Clark model 48201; Neenah, Wisconsin), duckbill masks (Kimberly-Clark 48220), procedure masks (Kimberly-Clark 47117), and fog-free masks (Kimberly-Clark 49214), each with particle filtration efficiency (PFE) at or above 97% and bacterial filtration efficiency (BFE) at or above 96%; fluid shield masks (Kimberly-Clark 48247, 47107, and 47137), each with PFE at or above 99% and BFE at or above 99%; and cone-style masks (Kimberly-Clark 00152), with PFE not available and BFE at or above 95%.¹ Event rates among institutions were comparable.