A change in the U.S. Centers for Disease Control and Prevention guidance for mask-wearing Friday means federal authorities no longer recommend indoor masking as a COVID-19 precaution for much of Southeastern Pennsylvania, including Philadelphia.

Whether that will change masking policy set by the health department in Philadelphia, the only place in the region with an indoor mask mandate, is uncertain.

The Philadelphia Department of Public Health said it would review the CDC’s new guidance, but the safety restrictions in place in the city are based on local conditions and “months of data specific to Philadelphia,” said Matt Rankin, a spokesperson for the department.

“At this time we plan to continue the implementation of these current response levels as the pandemic unfolds,” he said.

Pennsylvania does not have a statewide indoor mask requirement.

The CDC changed its guidelines for masking Friday because easy access to vaccines and testing, better treatments for COVID-19, and widespread immunity have “moved the pandemic to a new phase,” the agency said in a news release. The agency’s recommendations were also being widely disregarded, with states increasingly ending COVID precautions despite 95% of U.S. counties falling into the CDC’s old definition of substantial or high transmission. The new guidelines break COVID-19 risk levels into categories of high, medium, and low by county. Indoor masking is recommended only at the high risk level.

The Philadelphia region, including neighboring counties in New Jersey, is in the medium risk level, and at that tier wearing masks indoors is not recommended but people at high risk should take precautions. The CDC does consider case counts in its new guidelines, but a county can have higher case counts and still not be considered at high risk. The other factors are the rate of new COVID-19 hospital admissions over a seven-day period, and the percentage of available, staffed hospital beds.

“Anybody is certainly welcome to wear a mask at any time if they feel safer wearing a mask,” CDC Director Rochelle Walensky said in a news briefing. “We want to make sure our hospitals are OK and people are not coming in with severe disease. ... Anyone can go to the CDC website, find out the volume of disease in their community, and make that decision.”

» READ MORE: Philly ends its vaccine mandate for indoor dining, citing declining cases and need to ease burden on businesses

The emphasis on hospitalizations, rather than cases, in determining the risk from COVID makes sense, said Anuradha Paranjape, an epidemiologist, professor of medicine, and vice chair of clinical affairs at the Lewis Katz School of Medicine at Temple University. Because the omicron variant is associated with less serious illness, and so many people in the Philadelphia area are vaccinated or have immunity through prior infection, a high case count doesn’t necessarily translate into a lot of hospitalizations. Many people using home tests to diagnose themselves with COVID-19 also makes public case numbers less likely to be accurate, she said.

“Looking at the case average and the case rate of change now is very different than looking at case average and case rate of change a year ago,” Paranjape said.

She also noted treatments for COVID are much more effective now than they were just last summer.

The medium risk level also doesn’t recommend masking in schools, instead suggesting communities use testing to screen people exposed to COVID in workplaces, including schools. But masking will remain mandated for Philadelphia schools for now, Rankin said. Other states, including New Jersey, have already ended mask requirements for schools.

The changes to the CDC’s guidance eliminates masking recommendations for much of the country. Just over a third of U.S. counties, home to about 28% of Americans, are in the high risk category, the Associated Press reported. Those counties should still mask indoors, according to CDC recommendations, though other guidelines for high risk counties are largely for people who are themselves at greater risk of serious consequences due to COVID because they are older or immunocompromised. In Pennsylvania, 15 counties, scattered mostly between the south, central, and northeast parts of the state, are considered at high risk. No New Jersey or Delaware counties are in the high risk category.

In the region, Bucks, Chester, Montgomery, and Philadelphia Counties’ risk assessment dropped from high transmission to medium under the new guidelines. Chester County’s dropped from substantial transmission to medium.

The American Medical Association said in a statement the new CDC guidelines reflect the effectiveness of vaccines in preventing serious illness or death from COVID, but that many Americans who have received vaccine doses are still susceptible to the virus because of their health conditions or age, and masks should still be worn in public indoor spaces.

“Although masks may no longer be required indoors in many parts of the U.S., we know that wearing a well-fitted mask is an effective way to protect ourselves and our communities, including the most vulnerable, from COVID-19 — particularly in indoor settings when physical distancing is not possible,” the statement said.

Philadelphia changed its approach to COVID-19 safety restrictions last week, establishing metrics for case counts, hospitalizations, positivity rates, and case trends to determine when mask and vaccine mandates would go into effect. The change ended the city’s vaccine requirement for indoor dining immediately, but the indoor mask mandate is still in place. Under the existing standard, the health department requires three of the following four conditions be met before the mask mandate ends: the daily count of new cases must be under 100, no more than 50 people with COVID-19 may be in the hospital, the testing positivity rate must be under 2%, and cases must have increased by less than 50% over the previous 10 days.

Though city health officials said the CDC’s changes won’t necessarily change Philadelphia’s mandates, the federal agency’s recommendations were a factor in setting the new benchmarks. The case count that warrants the city’s mask mandate is the same metric the CDC used to define substantial transmission, city officials have said.

As of Tuesday, Philadelphia averaged 102 new cases daily, had 222 new hospitalizations, and the positive test rate was 2.3%.

City Health Commissioner Cheryl Bettigole anticipated the city’s mask mandate could end in a matter of weeks under the city standards. The health department set a lower bar for ending the vaccine mandate first, officials said, because that requirement was seen as more disruptive for city businesses. Hotels and event venues have said they’ve lost business to suburban facilities that don’t have this requirement.

The Associated Press contributed to this article.