In the news story “Conflict emerges over value of handwashing,” 1 a 2007 report, Influenza Transmission and the Role of Personal Protective Respiratory Equipment: An Assessment of the Evidence, is referenced as reason to cast doubt on the benefits of handwashing as a method for preventing the transmission of influenza and for supporting the use of N95 respirators in protecting the public. The report states that no evidence has been found that hand hygiene or other interventions prevent the transmission of influenza.
This ignores the substantive body of evidence that does support a role for hand hygiene in decreasing the likelihood of acquiring a respiratory tract infection (RTI), including severe RTI by more than 50% (OR 0.45). 2 The value of hand hygiene in preventing RTI was clearly stated in a 2007 Cochrane Review. 3 The 2007 report does not appear to make any recommendation on whether an N95 respirator should be worn in preference to a surgical mask to prevent influenza, nor does it cite any literature to support the use of either device in preventing influenza. The Cochrane Review found limited evidence of the effectiveness of N95 respirators over surgical masks.
A recently published randomized Canadian study demonstrated non-inferiority of surgical masks compared to N95 respirators in protecting health care workers from seasonal influenza. 4 Given the superior filtration capacity of N95 respirators compared with surgical masks, one explanation for this finding is that contact transmission prevented by hand hygiene and respiratory droplets may be the predominant means of transmission of influenza rather than small particle aerosols.
We acknowledge that new information will emerge as this pandemic unfolds. We also acknowledge the need to debate issues. But to pass off simple measures, for which there is an evidence base, and suggest others for which there is no evidence at all does health care workers and the public a disservice.
Footnotes
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For the full letter, go to: www.cmaj.ca/cgi/eletters/cmaj.109-3066v1#217416