N95 and KN95 respirator masks reduce the odds of testing positive for Covid-19 by 83% compared to 66% for surgical masks and 56% for cloth masks, according to a real-world study published Friday by the U.S. Centers for Disease Control and Prevention, reinforcing efforts to phase out cloth masks in favor of more effective face coverings.
Researchers affiliated with the University of California at Berkeley and the California Department of Public Health determined that any kind of mask offers significant protection against Covid and that it’s “most important” to wear a properly fitting mask that can be used consistently.
These findings reinforce the need to improve access to high-quality masks and to ensure access is not a barrier to use, the researchers said.
The study ran from February 18 to December 1 and included 3,039 California residents.
Previous lab tests have suggested that community-level masking requirements reduce Covid rates and that masks help prevent wearers either from contracting the disease or from passing it on to others. These findings reinforce a 2020 real-world study carried out on the aircraft carrier USS Theodore Roosevelt, where crew members who wore masks during a Covid outbreak had a 55.8% chance of being infected and those who did not wear masks had a roughly 80% chance of being infected. However, data on the efficacy of cloth masks has proven inconsistent—while the CDC found cloth masks 56% effective, a study of Bangladeshi villages found cloth masks only 5% effective, according to Smithsonian magazine. Such findings have prompted a shift in messaging toward promoting surgical and respirator masks. During the spread of the highly transmissible omicron variant, which now accounts for 99.9% of cases in the U.S., the School District of Philadelphia, Cornell University, the University of Arizona, the University of Southern California and other schools announced they would require students to wear surgical or respirator masks rather than cloth masks. Some airlines, including Air France, Lufthansa and Swiss International Air Lines, have also banned cloth masks in favor of more effective face coverings.