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The head of the US Centers for Disease Control and Prevention is standing by the agency’s mask guidelines, emphasizing Tuesday that now is not the time to change the recommendations or loosen restrictions aimed at preventing Covid-19.

The CDC “still recommends that all schools encourage students to wear well-fitting masks consistently and while indoors. And that’s consistent with our guidance that still also recommends that people mask in public indoor settings in areas of high or substantial transmission,” CDC Director Dr. Rochelle Walensky said in a radio interview with WYPR’s Tom Hall on Tuesday’s edition of the show “Midday.”

“Right now, we still have about 290,000 cases every single day, and our hospitalization rates now are higher than they even were at the peak of our Delta surge,” Walensky said. “So in this moment – while we are looking ahead and planning ahead, and we’ll continue to evaluate and follow the science – our recommendations are consistent with encouraging students to wear well-fitting masks.”

A growing number of states, from California to Delaware, have announced this week their intentions to drop indoor mask mandates in the coming days. Some others, like Connecticut and New Jersey, are eliminating mask mandates in schools.

Walensky noted that states and municipalities can determine their own policies.

According to the CDC, 99% of US counties still have high levels of coronavirus transmission. Walensky said she was cautiously optimistic about case numbers dropping from the peak of the Omicron surge but said that at the moment, those numbers are still too high for the agency to consider lifting any mitigation measures.

“We owe it to our children to make sure that they can safely stay in school. Right now, that includes masking. We’ve seen outbreaks that have occurred in communities where students were not masked in schools and had to close,” she said. “And much of our guidance is based on the amount of community transmission.”

Some governors and public health experts have called for the White House to release guidance on what Covid-19 metrics could help determine the appropriate time to lift measures and transition out of the pandemic phase and into an endemic phase. But there is no specific number of cases that Walensky considers as a benchmark for changing guidance.

“I don’t necessarily look at a magic number. What I do think is a really important barometer is how our hospitals are doing,” Walensky said.

“Are hospitals able to, you know, take care of the car accidents, the heart attacks and strokes that routinely walk in the door because they are not at capacity taking care of patients with Covid-19? And right now across the country, our hospitals are still in crunch mode,” she said. “They still have real challenges with capacity.”

Public health experts forecast that eventually, Covid-19 could become “endemic,” meaning the disease has a constant presence in a population but isn’t overwhelming health systems, stressing hospitals or affecting an alarmingly large number of people, as typically seen in a pandemic.

About 108,000 people are currently hospitalized with Covid-19, according to data from the US Department of Health and Human Services.

Masks should be worn indoors for a few more weeks, other experts say

People should continue wearing masks indoors for a few more weeks, Dr. Paul Offit, director of the Vaccine Education Center at The Children’s Hospital in Philadelphia, said Tuesday. He added that although the Covid-19 situation is improving, cases and deaths remain high.

“Right now, we have about 90% population immunity, meaning people who have either been naturally infected or immunized or both – that’s good. We’re moving into the warmer climates – that’s good. This is really basically, at its heart, a winter virus. The numbers are way down from where they had been – that’s good. But you still had 150,000 cases yesterday and 1,000 deaths. That’s still a lot of cases and deaths,” Offit told CNN’s Bianna Golodryga on CNN Newsroom.

“So, what I would say is, independent of whether there’s mandates or not, I think people should reasonably wear masks when they’re indoors for the next few weeks, until we’re much farther down then where we are right now,” Offit said. “We’re almost there, if you could just hang in there for a few more weeks.”

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A World Health Organization official also has urged people to keep wearing masks indoors.

“We are recommending to continue to wear masks, particularly when you’re in close proximity with other people, but especially when you’re indoors and even if you’re vaccinated,” Maria Van Kerkhove, WHO’s technical lead for Covid-19, said during a social media Q&A session Tuesday.

“We are still allowing this virus to circulate in some situations unchecked, and that’s dangerous,” she said. “We shouldn’t be doing that three years into this pandemic.”

CNN’s Carma Hassan contributed to this report.