Despite initial reports, a new study now suggests that surgical masks appear to be just as effective as N95 respirators when it comes to shielding health-care workers from flu infection.
The N95 respirator is a protective mask that filters out 95 per cent of airborne particles.
Following the rise of the H1N1 flu virus, the Ontario Ministry of Health and Long-Term Care recommended the use of the device for all health-care workers caring for a patient with influenza-like illness.
The researchers from McMaster University have found that surgical masks have an estimated effectiveness within one per cent of N95 respirators, and are not associated with an increased rate of infection of influenza or other respiratory viruses.
"Given the likelihood that N95 respirators will be in short supply during a pandemic and unavailable in many countries, understanding the relative effectiveness of personal respiratory protective equipment is important," said Dr. Mark Loeb, the principal investigator of the study and a professor in the Michael G. DeGroote School of Medicine at McMaster University.
During the study, researchers enrolled 446 nurses in emergency departments, medical units and pediatric units at eight hospitals in Ontario during the 2008-09 flu season.
They were randomly assigned to two different groups - 225 received surgical masks and 221 received N95 respirators.
The nurses were asked to begin using the surgical mask or the N95 respirator when caring for patients with influenza-like illness at the beginning of the influenza season.
In both groups, less than a third of the nurses had received the flu vaccine.
The study showed that influenza infection occurred in 50 nurses in the surgical mask group and in 48 in the N95 respirator group.
The researchers concluded that in routine health-care settings, particularly where the availability of N95 respirators is limited, surgical masks are as effective in protecting against influenza.
"It's certainly good to know that the protective effect of a surgical mark appears to be, based on our data, similar to the N95," said Loeb.
The study appears in Journal of the American Medical Association (JAMA).