CDC revises guidelines on who should mask indoors

Close to 3 in 10 Americans should continue wearing masks in indoor public areas, including schools, the Centers for Disease Control and Prevention said Friday, based on new guidance that incorporates federal COVID-19 data from hospitals. 

The agency’s new recommendations come as a growing number of places have already moved to lift mask requirements, as cases plummeted in the wake of the Omicron variant wave last month. The changes represent one of the largest shifts in the agency’s COVID-19 guidance in months, since the CDC said last year that even vaccinated Americans should wear masks indoors in areas deemed by the agency to be at “substantial” or “high” levels of transmission. 

Now, Americans in parts of the country deemed to have “low” levels of the disease — currently about 29.5% of the population — no longer need to wear masks indoors, according to the CDC’s new framework. Residents of counties at “medium” risk — around 42.2% of the country’s population – should wear masks if they are at heightened risk of severe disease, like those who have compromised immune systems. 

“Communities can use these metrics, along with their own local metrics, such as wastewater surveillance, emergency department visits, and workforce capacity, to update and further inform their local policies,” the CDC’s Greta Massetti told reporters Friday in a press briefing discussing the new measures.

While the daily pace of new cases has slowed by more than 90% nationwide from the peak of the Omicron wave last month, the vast majority of counties had still been in the red zone of “high” transmission by the agency’s original COVID-19 metrics. 

Those thresholds date back to the first year of the pandemic, before vaccinations, prior infections, and growing supplies of effective treatments for the disease blunted the severity of the threat. 

“With widespread population immunity, the overall risk of severe disease is now generally lower. Now, as the virus continues to circulate in our communities, we must focus our metrics beyond just cases in the community and direct our efforts toward protecting people at high risk for severe illness, and preventing COVID-19 from overwhelming our hospitals,” CDC Director Dr. Rochelle Walensky said. 

Walensky and Massetti said the agency believes the framework has “demonstrated predictive capacity” for trends in the virus, and will be updated weekly on a county-by-county basis. The new guidelines give more weight to the rate of hospitalizations in a community rather than merely the number of infections. Even at low levels of new COVID-19 cases, counties can be deemed at “high” risk if they see at least 20 new COVID-19 hospital admissions per 100,000 residents, or if at least 15% of available beds in hospitals are taken up by COVID patients.

The average number of COVID-19 patients in hospitals has fallen more than 60% from the record high set during the Omicron wave last month. For those who were hospitalized, studies published by the agency suggest patients were less likely to face severe illness with Omicron compared to the Delta variant. 

Many parts of the country had already moved to ease their mask rules ahead of the CDC’s new guidance, from lifting statewide mandates to rolling back rules in schools, based on similar assessments of the disease’s danger.

“Omicron was a game changer, when it wasn’t just about the number of cases that you had in a community but it was really about what the severity of disease was,” said Dr. Umair Shah, Washington state’s secretary of health, in an interview ahead of the final guidance being published. 

Washington state announced plans earlier this month to lift indoor mask requirements in March. Shah said the CDC had held “ongoing discussions” with state health officials around the country as they drafted their new metrics, but had not shared the final details of how their guidance would strike a balance for recommendations protecting vulnerable people in situations like schools and workplaces.

“We’re the ones who have to interpret or implement what the guidance is. What has happened here is that CDC spent multiple efforts to visit with state health officials, ongoing meetings to discuss with them, what does the future hold?” said Shah. 

The agency said their new COVID-19 metrics will “inform” new recommendations, but did not  offer details on how specifically the agency’s guidance might change. For now, masks remain required in schools in areas of “high” levels of disease, as well as in airports and trains.

Federal health officials say they consulted a broad array of outside experts and local officials in formulating their new recommendations. It comes amid a larger effort dubbed “COVID Next” to reevaluate their surveillance strategies to be “appropriate for this current stage of the pandemic.”

For example, a coalition of public health organizations announced last month that they backed ending widespread COVID-19 contact tracing, as some state and county health authorities had already done, in exchange for “a more strategic approach of outbreak investigations and targeted case investigations.” 

Amid concerns that growing use of rapid at-home tests would distort federal tallies of the virus, which are based on COVID-19 tests done by labs, the CDC has also touted efforts to ramp up alternative ways to monitor trends in the disease like testing samples of sewage to measure levels of the virus in wastewater. However, not every community has access to that data.

“We reviewed all data sources and really assessed them against several criteria, including do they measure severe disease or healthcare strain? How well do they provide data that is available at the local level, where it can really inform local decisions?” said Massetti. 

Federal health officials caution that rapidly slowing COVID metrics could be reversed if new variants of concern arise. 

BA.2, the Omicron sub-lineage that has grown to dominate infections in some countries abroad, has slowly grown to make up around 4% of new infections in the U.S. 

While international health authorities say there is not clear evidence that BA.2 leads to more severe infections, data from several countries suggest it could spread faster. The Food and Drug Administration has also questioned whether at least one of the currently effective monoclonal antibody drugs will work against the subvariant.

“We want to give people a break from things like mask wearing when levels are low, and then have the ability to reach for them again should things get worse in the future,” Walensky said.