N95 masks are just as effective as surgical masks, new findings show

November 3, 12:55 AMRichmond EMS ExaminerElle Künstlerin

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Is this man properly protecting himself? Image credit/copyright adamci

There has been much controversy about what kind of masks would be the most effective against the gargantuan pandemic that is surely going to come of this H1N1 scare.

A study at University of New South Wales in Australia published earlier this year showed that "N95 respirator masks prevented 75% of respiratory infections for high-risk healthcare workers, but regular surgical masks didn't appear to be effective against respiratory infections at all" according to Crystal Phend, Senior Staff Writer for MedPage Today.  In a randomized trial researchers reported that the N95 masks were still more effective even if there was an ill-fitting mask worn.  The original study also found that surgical masks were no better than the controls at preventing clinical respiratory illness or flu-like illness.  Some have suggested that the CDC's recommendation of N95s over surgical masks for healthcare workers came from the results of this study.

However, in direct contradiction with and just on the heels of the first study, a Canadian team out of McMasters University in Hamilton, Ontario, found that the two masks were equally effective at preventing flu-like illness.  In the report in the Journal of the American Medical Association, nurses who wore surgical masks had a 23.6% illness rate versus 22.9%, for the N95 group.

It seemed like the N95 versus surgical mask debate would never be definitively put to rest.  Until this week, that is.  The team from University of New South Wales in Sydney retracted their earlier findings at the annual meeting of the Infectious Diseases Society of America.  In an article on ABCNews.com, author Michael Smith quotes Dr. Neil Fishman of the University of Pennsylvania as saying, "The original Australian finding was a surprise to many experts because it did not accord with other findings or with clinical experience."  After many critiques and questions, the Australians decided to look over their data once again, and excluded the control group because it was not randomized.  When they did that, their findings concurred with the Canadian study and clinical experience:  N95 masks are no more effective than surgical masks at reducing the risk of flu-like illness.  Dr. Fishman believes this is because the flu is spread by large droplets that are blocked by a surgical mask.  The latest update on the CDC website is from September 24, 2009, so it appears that they have not reacted to the new findings.

What does this mean for EMS agencies and fire departments?  If one follows the CDC's recommendations, then every employee with patient contact needs to wear a fit-tested N95 mask.  The drawback to it is that N95's are very expensive, especially when compared to the price of surgical masks.  Alternatively, if one reaches a conclusion based on these and other studies with similar findings, surgical masks are adequate to reduce the rate of flu-like illness in the healthcare provider--with one caveat.  Surgical masks are not recommended during intubations because of the potential areosolization that the mask cannot protect against.  Being able to choose surgical masks and feel confident that they will protect providers will surely relieve some stress for agency supply managers.  Larger agencies like Henrico Fire or Richmond Ambulance Authority have the money to provide fit-tested masks to all employees.  However, smaller, rural volunteer squads with limited funds and a low call volume are wasting money they cannot afford to waste.  OMDs and infection control officers at the agency, council and state level need to look at these studies and possibly change their recommendation.

Sources:

1. Crystal Phend, "Medical News: ICAAC: Surgical Masks Don't Prevent Infection."  MedPage Today.
2. Crystal Phend, "Medical News: Study Shows Surgical Masks Equal Respirators for Healthcare Workers."  MedPage Today.
3. Michael Smith, "Flu Mask Decision Based on Flawed Study, Authors Say."  ABCNews.com.
4. Michael Smith, "IDSA: N95 versus Surgical Mask Findings Retracted."  MedPage Today.
5. Mark Loeb, MD, MSc, et al, "Surgical Mask vs N95 Respirator for Preventing Influenza Among Health Care Workers A Randomized Trial."
6. Centers for Disease Control, "CDC H1N1 Flu | Interim Recommendations for Facemask and Respirator Use to Reduce 2009 Influenza A (H1N1) Virus Transmission."  Centers for Disease Control website.

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