CDC says N95 masks offer far better protection than cloth masks against omicron variant

The Centers for Disease Control and Prevention provided its most explicit guidance to date Friday on the superior protection offered by N95 masks compared to cloth coverings and other masks.

But the agency stopped short of recommending that people opt for N95 masks in updating its mask guidance. Officials have always maintained that the best mask is the one that fits well and is worn consistently.

The latest CDC information ranks the different levels of protection afforded by different masks and how they should be used. "Loosely woven cloth coverings" offer the least protection, the updated guidance says. Well-fitting disposable surgical masks and KN95 masks offer still more protection. And well-fitting respirators, including N95 masks, which are approved by the National Institute for Occupational Safety and Health, "offer the highest level of protection."

Both N95 and KN95s are considered respirators that filter out most virus particles - and come with markings to indicate they are authentic. Both types of masks must form a seal to the face to work properly.

N95 masks, which are approved by NIOSH, are designed to filter up to 95% of particles, as their name implies. KN95s are supposed to meet a comparable Chinese standard, but there is no Chinese regulatory agency ensuring that, according to Anne Miller, executive director of Project N95, a nonprofit organization that distributes free N95s and children's masks in the United States. However, U.S. firms make high-quality KN95s, she said.

In a statement, CDC said it updated its website to "lay out the protection provided by available masks and respirators, noting that some provide better protection than others." The updates, the agency said, "reflect the science on masking, including what we have learned in the past two years, and will provide people the information they need to improve how well their masks or respirators protect them."

The CDC continues to say that specially labeled surgical N95s should be reserved for use in health-care settings. But certain people, including bus drivers and grocery store workers and others who interact with people who don't consistently wear masks, may want to use nonsurgical N95s or KN95 masks, the guidance states. Well-fitting N95s or KN95s may also be appropriate for someone caring for an immunocompromised or sick person.

The exact wording of the update has been the subject of email discussion and multiple revisions between the CDC and officials at the Department of Health and Human Services this week, according to an administration official who spoke on the condition of anonymity because they were not authorized to speak about the process.

Earlier in the week, the CDC was weighing stronger language around the use of N95 or KN95 masks for people who are able to wear them consistently.

On Thursday, President Joe Biden said high-quality masks would be provided free to all Americans. The White House is expected to announce the details next week, including what type of masks the government will be providing.

With the highly transmissible omicron variant spurring record levels of infections and hospitalizations, experts have repeatedly urged the Biden administration to recommend that people use better-quality masks to protect against an airborne virus, and to underscore the importance of masking.

When the CDC issued its initial mask guidance in 2020, health officials did not urge their use out of concern that health workers might be unable to get them. But health officials said there are no longer serious shortages of N95 masks -- a fact also made clear on the CDC website.

CDC has worked on the update for several weeks, but completion hinged on the government's analysis of the mask supply chain, which was recently completed, according to an official close to the deliberations.

As of Dec. 29, the United States had 747 million N95 masks in the national stockpile, 59 times pre-pandemic levels, according to prepared testimony from Dawn O'Connell, assistant secretary for preparedness and response, at a Tuesday Senate committee hearing.

N95s and KN95 masks are more readily available two years into the pandemic, but they still cost much more than cloth masks.

"This cost barrier can exacerbate already significant health inequities," said the Infectious Diseases Society of America in a statement about the updated CDC information. The organization said it was encouraged by Biden's announcement that the administration will soon make high-quality masks available for free.