A new study out of Oregon Health & Science University (OHSU) funded by the World Health Organization has confirmed what much of the medical community has assumed. Yes, even stock surgical masks, which are not designed to filter particles from the air you breathe in, appear to make significant reductions in the numbers of doctors and nurses infected by coronaviruses in clinical settings. Meanwhile, N95 respirators, which are designed to filter pathogens, along with full protective gear including face shields and gloves, may help even more.

The paper, led by Roger Chou, director of the Pacific Northwest Evidence-based Practice Center at OHSU and a professor of medicine in the OHSU School of Medicine, was a meta-study that analyzed the results of 64 separate studies about the impact of PPE on virus transmission. They date back to 2003 with the rise of SARS, account for data on MERS (first reported in 2012), and even included a few early studies on SARS-Cov-2 (the virus that causes COVID-19).

“We were trying to take the evidence from viruses that we thought would be most like COVID-19,” Chou says, noting that all of the analyzed studies examined novel coronaviruses, which caused similar upper respiratory symptoms. The conclusion? “PPE definitely did seem to help,” he says. “In terms of the impact . . . in general, if you look at [individual healthcare workers] using masks versus no masks, the risk of being infected drops by anywhere from 50% to 80%.”