Anthony Fauci, the White House chief medical adviser, said on Sunday top US health officials were discussing whether to revise mask guidance for Americans vaccinated against Covid-19.

“This is under active consideration,” Fauci told CNN’s State of the Union, though he also emphasized that local governments can issue their own rules under current guidance from the Centers for Disease Control and Prevention (CDC).

Los Angeles county and St Louis, Missouri, have reinstated indoor mask requirements and other cities are weighing whether to do the same.

After a significant drop in Covid-19 cases because of the national vaccine campaign, infections are rising in all 50 states and Washington DC. The increases are highest in states with large groups of unvaccinated people. More than 610,000 have died from Covid-19 in the US.

At a White House on Thursday the surgeon general, Vivek Murthy, said 97% of hospital admissions and 99.5% of Covid deaths were occurring among unvaccinated people.

More than 162.7 million Americans are vaccinated – or 49% of the population, according to the CDC.

Fauci said local leaders, particularly in areas with low rates of vaccination, needed to lead outreach efforts to get people vaccinated.

He highlighted recent work by two prominent Republicans who have repeatedly criticized him: a Louisiana representative, Steve Scalise, and the governor of Florida, Ron DeSantis.

“​​I was very heartened to hear people like Steve Scalise come out and say, ‘Hey, we’ve got to get vaccinated,’” Fauci said. “Even Governor DeSantis right now in Florida is saying the same thing. We’ve got to get more people who relate well to the individuals who are not getting vaccinated to get out there and encourage them to get vaccinated.”

Among those reporting they definitely won’t get vaccinated, 23% are Republican, 16% are independent and 2% are Democrats, according to the Kaiser Family Foundation vaccine monitor.

DeSantis sells merchandise which mocks masks and Fauci, but cases in Florida are the highest they have been since January.

“These vaccines are saving lives,” DeSantis said last week.

Scalise, the House Republican whip, was vaccinated last week and told the New Orleans Times-Picayune he had waited because he thought he had some immunity from an earlier Covid-19 infection. But the rise of the Delta variant appeared to sway him.

“When you talk to people who run hospitals, in New Orleans or other states, 90% of people in hospital with Delta variant have not been vaccinated,” he said. “That’s another signal the vaccine works.”

Fauci said the administration was reviewing whether some vaccinated people may require booster shots. Vulnerable people such as organ transplant and cancer patients were “likely” to be recommended for booster shots, he said.

From Missouri, a local mayor told CBS’s Face the Nation some prominent local figures were still speaking out against the vaccine.

“We continue to have to push back against negative messaging,” said Quinton Lucas, mayor of Kansas City.

Lucas said the focus in Kansas City was on getting people vaccinated and that his city did not currently have plans to re-introduce mask requirements, though it was something he had considered.

“I think every mayor in a major city in America is wondering if it is time to return to mandates,” Lucas said.

Jerome Adams, the US surgeon general under Donald Trump, told CBS the CDC should change guidance to vaccinate and mask in places with lower vaccination rates, an argument he also made in an editorial for the Washington Post.

Adams wrote that he initially agreed with the CDC’s guidance in May that vaccinated people no longer needed to wear masks, hoping it would encourage vaccinations.

“In hindsight, it’s clear that the message many Americans heard was that, vaccinated or not, masks were gone for good,” Adams wrote.

On CBS, Adams compared the situation to when public health officials last year told people to not use N95 masks because they needed to be reserved for medical professionals.

In hindsight, he said, he wished that guidance had been less definitive because many interpreted it as a signal that masks didn’t work.

“We need to learn from what happened in the past,” Adams said.