(CNN) — The Biden administration is debating a series of steps to further contain the Covid-19 pandemic, which, after 18 months, is again surging in parts of the country where vaccination rates are low.

A senior administration health official said the government is “actively exploring” how to provide extra vaccine shots to vulnerable populations, who officials now increasingly expect will require boosters, as they await the US Food and Drug Administration’s full approval of the three vaccines currently authorized for emergency use. The White House on Friday announced a purchase of hundreds of millions of additional Pfizer doses, in part to be prepared in case the booster shots are needed.

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Discussions are ongoing over whether to revisit mask guidelines, a decision officials say will be left to the US Food and Drug Administration and the US Centers for Disease Control and Prevention, but that nonetheless comes loaded with political baggage after the celebratory lifting of mask mandates this spring. White House aides said they did not believe any new recommendations were imminent but acknowledged they have previously received little warning when the CDC updates its guidelines. According to sources familiar with internal discussions, the health agency is reconsidering its stance on mask orders.

And Biden himself is facing pressure to back vaccine requirements among certain groups of people or in particular places, a step his team has so far been reluctant to get behind even as other leaders, including in Europe, have seen their countries’ vaccination rates rise after making such a move.

Ultimately, curbing the current spike is hampered by continued vaccine hesitancy in certain pockets of the country, a problem underscoring the limits of the President’s ability to control the pandemic. Biden has been explicit in declaring the current outbreak “a pandemic among the non-vaccinated” — stressing that current hospitalizations and deaths are almost exclusively among those who have not gotten the shots.

But as reports of breakthrough cases, almost all of them mild, in vaccinated people become more frequent — including this week in a White House aide — the administration is looking for further ways to rein in the virus.

“What’s happening now is all the major scientific operations in this country and the 25-person group we put together are looking at all the possibilities,” Biden said on Thursday, describing an all-hands approach to the situation.

The war’s not done

He was speaking after receiving an Oval Office briefing from his Covid team that ran well past its allotted time. Biden receives daily updates on current numbers and has questioned his staff for information about the highly contagious Delta variant and vaccination rates around the country.

“What they’re doing is they’re going into — investigating every aspect of any change that could or might take place,” Biden said after the meeting. “But the vaccines are good against all of the variants that are out there, including the Delta variant.”

A day later, the White House said it had purchased an additional 200 million doses of Pfizer’s vaccine, in part to prepare for the potential that boosters will be recommended once more data is generated from ongoing studies.

The White House said the purchase was also in anticipation of authorization for the vaccine’s use in children under 12, which Biden said during a CNN town hall this week that he expected to happen “soon” but health experts believe won’t come until later on in the year, or possibly in 2022.

In a statement Friday, the CDC said it was “exploring multiple options for how to make a third dose possible for the immunocompromised if needed.” Among administration health officials, the prospect of requiring a third dose of the Pfizer or Moderna vaccines is viewed as an increasingly likely scenario as new reports suggest the vaccines’ efficacy is limited for people with compromised immunity.

The preparation for possible booster shots, combined with discussions about revisiting mask recommendations, are the latest ways the administration is working to contain a pandemic that only weeks ago appeared to be waning. Biden has worried that the spike in cases could erase hard-fought gains against the pandemic, which he is expected to use as a political talking point over the coming year.

Forty-eight states have seven-day averages of new cases that are at least 10% higher than the week before, according to data from Johns Hopkins University. Only 48.8% of the US population is fully vaccinated.

Biden and his aides have so far been careful to avoid pinning outright responsibility for the situation on those Americans who have declined to be vaccinated. “I don’t think our role is to place blame,” press secretary Jen Psaki said Friday.

But as the potential for new restrictions — even for vaccinated people — emerges in individual states and cities, Biden has faced pressure to put more of the onus on the unvaccinated to bear the brunt of the new requirements. He and his team have debated and rejected the idea of vaccine passports and are still wary of efforts that would require individuals to provide proof of vaccination.

Pressure grows over vaccination requirements

That stands in contrast to leaders like France’s Emmanuel Macron, who is trying to coerce his population into getting vaccinated by making life extraordinarily difficult for those who don’t. His announcement that proof of vaccination will be required for most indoor public venues — including cafés — spurred angry protests but also a major surge in vaccination appointments.

In the United States, officials are still weighing how much backing to give businesses and organizations that require vaccines for their employees or apply outsized consequences on those who choose not to get shots.

That balancing act was on display Friday when Psaki was asked about the NFL’s memo released Thursday that stated that any game delayed by a Covid-19 outbreak among unvaccinated players or staff members that can’t be rescheduled will result in a forfeit for the team responsible for the outbreak. The memo also stated that players from both teams won’t be paid for that week’s game if it must be canceled.

Psaki said she wouldn’t make a “sweeping private-sector conclusion” about whether the memo was appropriate but that “This is guidance they determined, the NFL, about how they’re going to proceed with their season. That is their role to do.”

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One former Biden aide said he thinks it’s time to turn up the heat on the unvaccinated.

“It’s going to take more than him to make the case. It’s going to take getting very aggressive,” said Andy Slavitt, who until recently was Biden’s senior adviser for Covid response.

He added, “If people say they don’t want to be vaccinated, which some people might say, I think it’s perfectly reasonable to say: ‘That’s fine. But we’d like you to show up every morning, an hour before work, and get a negative test, maybe even at your own expense,’ until the point where people will say: ‘You know what? It makes more sense to actually get vaccinated.’ ”

A tricky discussion on masking

Absent more aggressive vaccine requirements, officials in several places — including Los Angeles — have been forced to return to earlier requirements on masks.

Renewed administration discussions about revisiting mask recommendations revolve around what messages on masking the White House should offer, and what guidance the CDC should issue, sources familiar with the matter say. White House officials have repeatedly said it will be up to the CDC whether to change official guidance.

“They have to do something,” one senior official said, noting the importance of public messaging amid mounting questions.

On masks in particular, a reversal of the loosened recommendations would dampen what had been a psychological milestone after more than a year of pandemic-era restrictions.

“We have to be honest that we’re asking people who are fully vaccinated basically to sacrifice, because it’s so hard to enforce mask-wearing based on vaccination status,” said Dr. Richard Besser, former acting director of the CDC and president and CEO of the Robert Wood Johnson Foundation.

“You do get some additional protection and we have seen some mild breakthrough cases, so that’s an added benefit. But if we had a fully vaccinated population, or highly vaccinated population, we wouldn’t be talking about needs for putting in place mask mandates again.”

After news emerged that the administration was discussing a change in guidelines, Psaki called the reports “breathless” and suggested talk of re-masking was premature — while still acknowledging the conversations were underway.

“We’ve never said that battle is over. It’s still ongoing. It would be more concerning, or should be more concerning, to all of you and the American people if we were not having those conversations,” she said.

Proactive purchases

Officials similarly described the purchase of the new Pfizer doses as proactive and said any recommendation on boosters would come from health experts.

Still, at a Thursday meeting of the CDC’s advisory panel on vaccines, officials said they were exploring ways to get additional doses — beyond the current one- or two-dose regimen — of the currently authorized vaccines to immunocompromised people. That includes people being treated for cancer and those who have had organ transplants or have HIV.

“FDA is actively exploring all regulatory options for providing access to additional doses of authorized vaccine in situations where data suggest that the benefit would outweigh the risks,” Dr. Doran Fink, from the FDA’s Center for Biologics Evaluation and Research, told CDC advisers in the meeting.

“This is truly an important scientific issue and an important public health issue,” Fink said about the possible benefit of extra vaccine doses for immunocompromised people.

Recent reports have suggested that Covid-19 vaccines are not effective enough in people with weakened immune systems, and last week the CDC revised its guidance for fully vaccinated individuals, warning people who are immunocompromised that the vaccines may not be as effective for them.

Earlier this month, Pfizer announced it would be seeking authorization to provide a third dose of its Covid-19 vaccine as a booster, citing data from Israel on the continued spread of the coronavirus and the limited efficacy against the more transmissible Delta variant.

Still, the CDC has not yet formally recommended boosters for anyone. And federal health officials, including Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, continue to say the US needs more data before recommending coronavirus vaccine boosters for anyone.

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