Amid falling case rates and state-level decisions to lift mask mandates, CDC on Friday updated its masking guidance for the first time since July 2021, with new metrics and loosened recommendations for masks in indoor public spaces in most areas of the country.

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CDC updates its masking guidance for Americans

Previously, CDC used a case-centric formula focused on rates of coronavirus transmission to determine which areas of the United States required strict health measures, such as masking. Masking and other health measures were recommended for anyone living in areas of substantial or high transmission. However, this approach was developed before Covid-19 vaccines and other treatments, which significantly reduce the risk of disease, were widely available.

In comparison, CDC's new metrics, which divided U.S. counties into areas of low, medium, or high risk, focus on a combination of an area's Covid-19 case rates, hospitalizations, and hospital capacity. In particular, the new metrics put more weight on whether Covid-19 hospitalizations in a certain area will potentially overwhelm hospitals.

Now, more than half of U.S. counties—which comprise more than 70% of the American population—are considered low or medium risk and will no longer be recommended to wear masks indoors.

Under the new guidance, CDC advised individuals who live in counties where the risk of the virus is high—currently around 28% of Americans—to continue wearing masks in indoor public venues, including schools.

For most people living in low- or medium-risk counties, CDC did not recommend masks in any setting. However, the guidance advised people who live in medium-risk counties or are at high risk from Covid-19 to talk to their health care providers about whether they need to wear a mask.

"Moving forward, our approach will advise enhanced prevention efforts in communities with a high volume of severe illness and will also focus on protecting our health care systems from being overwhelmed," CDC Director Rochelle Walensky said on Thursday.

Separately, a senior administration official told Politico that CDC's new approach is "going to be much more on what the responsibility of the people at the local level is," adding that it is "less mandating and more leave it up to the local authorities. We're just going to give you the data."

Some experts, health systems voice concerns about CDC's loosened mask guidance

 Following CDC's announcement, some health experts expressed concerns about whether it is still too soon to loosen masking recommendations for the public.

"I recognize the growing frustration and impatience to get beyond masking and some of the restrictions that have been placed during the pandemic," said Lisa Maragakis, senior director of health care, epidemiology, and infection prevention for the Johns Hopkins Health System. "But as an infection prevention expert, it feels too early, and I worry that pulling back too quickly on our safety precautions in setting up the conditions for another surge."

In addition, several health systems, including the University of Pittsburgh Medical Center and Kaiser Permanente, have indicated they will continue to require masks for their staff, patients, and visitors to reduce the risk of viral transmission.

"My hope is that the vast majority of them will continue to understand that it's prudent to wear masks, at least for a bit longer in the health care setting," Maragakis said.

Separately, Richard Martinello, the medical director for infection prevention at the Yale New Haven Health System, said it will be important for public health experts and providers to remind people that not all masking guidance is applicable everywhere, and that stricter guidance may be necessary if Covid-19 cases begin to surge again.

"I think a lot of people think the pandemic is over right now," said Jeffrey Duchin, health officer for the Seattle and King County public health department. "And that's, I think, tragic." (Haslett/Flaherty, ABC News, 2/25; Miller, Associated Press, 2/25; Cancryn/Owermohle, Politico, 2/24; Owens, Axios, 2/25; Mandavilli, New York Times, 2/24; Vakil, The Hill, 2/24; Lovelace Jr./Edwards, NBC News, 2/24; Cohen/Howard, CNN, 2/25; Branswell, STAT News, 2/25 [1]; Branswell, STAT News, 2/25 [2]; Devereaux, Modern Healthcare, 2/25)