Study finds N95 respirators better than masks for protection against viruses
A new study comparing the effectiveness of N95 respirators and surgical masks suggests that N95 respirator strongly outperform surgical masks in shielding hospital workers from influenza viruses and other microbes. The study, produced by an international team led by Raina MacIntyre from the University of New South Wales, Australia, involved 24 hospitals and 1,936 front line hospital healthcare workers in Beijing, China. It found that the surgical masks had no efficacy, whereas the N95 masks were significantly more protective than a control.
Subjects wore masks for four weeks during winter and were followed for development of illness for five weeks. Symptomatic subjects were tested for respiratory viruses including influenza. Outcomes were clinical respiratory illness (CRI), influenza-like illness (ILI), any laboratory confirmed respiratory virus infection, and laboratory confirmed influenza. Not yet published in full, the study was reported at an American Society for Microbiology meeting in San Francisco. It aimed to compare the clinical efficacy of surgical masks, N95 masks (fit tested) and N95 masks (non fit tested) compared with control in front line healthcare workers. It claims to be the first randomised controlled trial comparing the effectiveness of N95 respirators and surgical masks.
N95 respirators are designed to fit closely to the face and filter out 95% of airborne particles, whereas surgical masks are looser fitting and were originally designed to prevent the wearer from infecting others. The study also found that fit testing did not improve the efficacy of N95 masks. However, health workers say the tight-fitting N95s are uncomfortable and difficult to wear for long periods. They are also more expensive to supply than surgical masks.
