# 3791
Just two weeks after Raina MacIntyre, head of public health at the University of New South Wales in Sydney, presented evidence at the ICAAC conference on the lack of protection offered by surgical facemasks (see A Surgical Mask Strike) we get another study, that this time seems to support the notion that surgical masks may offer protection against influenza infection.
Given the reported shortage of N95 masks and reluctance of some health care workers to wear them for long periods of time, many health care facilities would like to move to the less expensive and easier to obtain surgical mask for staff not performing aerosol generating procedures on influenza patients.
Yesterday the NEJM published a perspective article (see NEJM Perspective: Respiratory Protection For HCWs) based on the recent IOM evaluation of surgical masks vs. respirators, and reiterated the advice:
Until more data are available, the committee recommends that clinicians reach for the N95 respirator when confronting patients with influenza-like illnesses, particularly in enclosed spaces.
Today JAMA (Journal of the American Medical Association) published a study which reports that HCWs using surgical masks experienced `noninferior rates of laboratory-confirmed influenza’.
The major implication here, according to the authors, is that surgical masks provide similar protection to N95 respirators in a routine health care setting.
The authors acknowledge certain limitations to their study, including an inability to determine whether those participants who became infected contracted influenza in the workplace, at home, or in the greater community. They believe that such exposures were balanced between both groups, however.
Obviously we are some distance away from reaching a consensus on this issue.
Here is a link, and excerpts, from the study’s abstract.
Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers
A Randomized Trial
Mark Loeb, MD, MSc; Nancy Dafoe, RN; James Mahony, PhD; Michael John, MD; Alicia Sarabia, MD; Verne Glavin, MD; Richard Webby, PhD; Marek Smieja, MD; David J. D. Earn, PhD; Sylvia Chong, BSc; Ashley Webb, BS; Stephen D. Walter, PhD
JAMA. 2009;302(17):(doi:10.1001/jama.2009.1466).
Results Between September 23, 2008, and December 8, 2008, 478 nurses were assessed for eligibility and 446 nurses were enrolled and randomly assigned the intervention; 225 were allocated to receive surgical masks and 221 to N95 respirators.
Influenza infection occurred in 50 nurses (23.6%) in the surgical mask group and in 48 (22.9%) in the N95 respirator group (absolute risk difference, –0.73%; 95% CI, –8.8% to 7.3%; P = .86), the lower confidence limit being inside the noninferiority limit of –9%.
Conclusion Among nurses in Ontario tertiary care hospitals, use of a surgical mask compared with an N95 respirator resulted in noninferior rates of laboratory-confirmed influenza.
The link to the entire article is:
Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers Published October 1, 2009.
A hat tip to Ironorehopper on Flutrackers for posting this link.
