Respirator masks are far more effective than others, a new analysis found.
A new analysis of 172 studies, funded by the World Health Organization, confirmed what scientists have said for months: N95 and other respirator masks are far superior to surgical or cloth masks in protecting essential medical workers against the coronavirus.
The results, published on Monday in The Lancet, make it clear that the W.H.O. and the Centers for Disease Control and Prevention should recommend that essential workers like nurses and emergency responders wear N95 masks, not just surgical masks, experts said.
“It’s been disappointing that both the W.H.O. and the C.D.C. have suggested that surgical masks are adequate, and they’re clearly not,” said David Michaels, a professor at George Washington University who headed the Occupational Safety and Health Administration under President Barack Obama.
“Reliance on surgical masks has no doubt led to many workers being infected.”
N95 masks offered 96 percent protection, the analysis found, while the figure for surgical masks was 77 percent. The findings are particularly important as the country moves to reopen the economy, Dr. Michaels said.
Workers in health care settings are not the only ones at high risk of coronavirus infection: employees in meatpacking plants and some farms are all at high risk of coronavirus infection, and could benefit from N95 masks as well, he said.
The W.H.O. has not endorsed universal wearing of face masks, although most of its member governments adopted the practice months ago. The organization’s stance has frustrated many public health experts who see masks as a simple, inexpensive and highly effective strategy to help contain the pandemic, especially given that the virus can be transmitted by people who do not know they are ill.
“When there is uncertainty and you don’t know everything about a disease, you have to be precautionary, which means you have to assume the worst and provide the best for health care workers,” said Dr. Raina MacIntyre, an epidemiologist at the University of New South Wales in Sydney, Australia, who wrote a commentary accompanying the paper.