Consistently wearing high-quality masks offers strong protection, study in California suggests

People who reported always wearing face masks or respirators, such as N95 masks, in public indoor settings were significantly less likely to later test positive for the coronavirus than people who said they never wore masks in such places, researchers at the California Department of Public Health reported Friday.

>> Emily AnthesThe New York Times
Published : 5 Feb 2022, 06:07 AM
Updated : 5 Feb 2022, 06:07 AM

The study, a phone survey conducted before omicron became the dominant variant in the United States, also suggested that surgical masks and N95 or KN95 respirators provided better protection than cloth masks.

The findings provide more evidence that wearing high-quality, well-fitting masks can help protect the wearer from infection with the virus. They come at a time when many school districts and local officials have begun considering whether and when to lift mask mandates.

“If the mask mandates are lifted, then it’s going to be incumbent upon the individual to do what they can to reduce the risk,” said Anne Rimoin, a public health researcher at the University of California, Los Angeles.

The new study, she added, “underscores the point that wearing a mask, wearing it consistently, will reduce your risk, and the higher quality mask that you wear, the better protection that you have.”

The study included more than 3,000 California residents who received PCR test results between Feb. 18 and Dec 1, 2021. Roughly half had tested positive for the virus.

Researchers called each participant within 48 hours of their test result. They asked whether they had been in public indoor settings in the 14 days before testing and, if so, how often they had worn a mask in those environments. A subset of participants, who enrolled in the final months of the study, were also asked what kind of mask they wore.

Among those who reported always wearing a mask, the odds of testing positive for the virus were 56% lower than among those who said they never did. Among those who specified the type of mask they wore, the odds of testing positive for the virus were 83% lower for those wearing an N95 or KN95 respirator, and 66% lower for those wearing surgical masks, compared with those who did not wear masks.

“Masks, especially N95s or KN95s, continue to be an effective tool to reduce the spread of COVID-19, along with getting vaccinated and boosted,” Dr Erica Pan, the state epidemiologist for the California Department of Public Health, said in an email.

The study has several limitations, including that it relied on self-reported behaviours and included only those who sought testing. It was also conducted before omicron was widespread, although Rimoin said she believed that the findings would continue to hold up for the new variant.

© 2022 The New York Times Company