President Biden repeats the phrase frequently. “We follow the science,” he pledged on a visit to the National Institutes of Health. “Follow the science,” he told staff at the Centers for Disease Control and Prevention. “This administration will follow the science,” he said during a White House event announcing the 50 millionth vaccine shot delivered to an American.

A week ago, the president did just that — strolling to the Rose Garden to trumpet new guidance from the CDC that fully vaccinated Americans no longer need to wear masks or socially distance in most instances.

But in following that scientific advice, the administration left out nearly everyone else — local and state health departments, labor unions, governors and numerous other public officials, many of whom were caught off guard by one of the most significant developments of the coronavirus pandemic.

President Biden spoke about the new CDC guidelines that fully vaccinated people do not need to wear masks indoors and outdoors in most cases on May 13. (The Washington Post)

And in Biden’s rush to share the mask news with little context or discussion, some White House insiders, Biden allies and public health experts worry that the administration may have inadvertently encouraged millions of unvaccinated Americans to stop wearing masks.

“This guidance may be quite appropriate as individual guidance, but it is not appropriate as guidance for community action,” said Tom Frieden, who was the CDC director under President Barack Obama.

“There was no urgency to change the mask guidance. That should have been done in a more planful way,” Frieden continued, adding: “I haven’t said that on the record before.”

Zeke Emanuel, a professor of medical ethics and health policy at the University of Pennsylvania, who was on Biden’s transition task force, was similarly critical.

“It wasn’t well done,” Emanuel said. “Slowing this down would have been the prudent thing to improve the communication and ensure that all the considerations that were needed on such a momentous decision were in fact taken into account, and that the administration had answers for the very, very obvious potential scenarios.”

The impact of the new guidance has been swift and far-reaching. At least 17 states dropped or pulled back their mask mandates for fully vaccinated people since May 13, according to a tally by AARP, and others are planning to implement changes in coming days. Mandates were dropped in places such as Connecticut and Vermont, which lead the country in vaccination rates, but also in states such as Nevada, where about a third of the population is fully vaccinated.

The rollout of the decision angered some governors. New York Gov. Andrew M. Cuomo (D) called out the Biden team during a private call on Tuesday, telling the White House it “should have been coordinated” on the messaging because it was “sensitive,” according to an official on the call who spoke on the condition of anonymity to discuss a private conversation.

The CDC is now scrambling to issue additional advice for parents with children who aren’t eligible for vaccines, businesses and summer camps, among others. The turbulence around the mask guidance is coming as the CDC is undergoing major changes with the departures of two longtime top officials, raising questions about the steadiness of an agency that’s been under fire for the past two years.

White House officials strongly defended their handling of the new mask guidance.

“We are making incredible progress in our efforts to combat the pandemic here in the U.S. thanks to a whole-of-government effort that is guided by science and the leadership of our public health officials,” White House spokesman Kevin Munoz said in a statement. “Hundreds of thousands of American lives were unnecessarily lost last year due to a response that sidelined public health officials and refuted science. That is not lost on the President, and his commitment to a wartime, science-driven response will remain unwavering until we finally defeat this virus.”

But the White House’s focus on avoiding interference in the CDC’s work has significant drawbacks, according to some senior officials and outside advisers, who spoke on the condition of anonymity to speak frankly about the internal workings of the administration.

When CDC Director Rochelle Walensky informed the White House of the updated mask guidance, for instance, West Wing officials asked what the agency would tell parents and businesses, but did not receive clear answers, according to a person briefed on the conversation. No one was willing to ask the agency to delay its guidance for more preparation, however, this person said.

“It’s their ethos and they’ve kind of swallowed their own talking points of science drives the process, ” said one outside adviser.

Walensky told Jeff Zients, the White House coronavirus response coordinator, about her decision to roll back the guidance around 6:15 p.m. on the evening of May 12, according to a CDC official.

Walensky made the formal announcement the following day at a 2 p.m. coronavirus briefing, mentioning the major news only after delivering the latest infection rates, heralding the release of $7.4 billion in funds for public health workers and noting her endorsement of using the Pfizer vaccine for 12-to-15-year-olds.

“If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic,” Walensky said. “We have all longed for this moment when we can get back to some sense of normalcy.”

Within hours, Biden gave an address to the country. “If you’re fully vaccinated and can take your mask off, you’ve earned the right to do something that Americans are known for all around the world: greeting others with a smile — with a smile,” Biden said.

Several allies said the problems that came up after the guidance was released — including concerns among business owners, governors and parents with young children who are not yet eligible for vaccines — were entirely predictable and should have been worked through ahead of time. For example, the guidance was immediately misinterpreted in many places as an end to all indoor mask mandates.

Allies and former Obama administration officials said in a conventional policy process, officials should ensure that such issues are dealt with before new health guidance is announced.

During the H1N1 scare in 2009, Rich Besser, the acting CDC director, briefed Obama and his top aides that hospitals in Mexico were overflowing and running out of supplies. But the following day, the CDC learned the crisis wasn’t quite as bad as they had feared.

Besser contacted the White House and spoke with senior Obama adviser David Axelrod, informing him that they could now back off some of the severe guidelines they had issued, including closing facilities for two weeks after the United States had its first suspected cases of H1N1.

“David said woah, woah, we cannot go from level 5 to level 1,” Besser recalled.

“There are times where you want speed, but you have to make sure there’s appropriate deliberation,” Besser added, referring to the Biden administration’s mask guidance.

Some Biden allies said the administration appears to have overcorrected for the unprecedented political interference the CDC faced under the Trump administration.

“There has to be a middle ground,” said Ann O’Leary, the former chief of staff to California Gov. Gavin Newsom and an ally of the Biden administration. “This isn’t just a scientific question. This is a decision about our public health.”

Anthony S. Fauci, the director of the National Institute of Allergy and Infectious Diseases, said in an interview that the CDC’s role in the administration is far more normal now than it was during the Trump years.

“The real outlier is not now, the outlier was in the last administration when the CDC’s role was diminished greatly,” said Fauci, who declined to comment on the handling of the new mask guidance.

And Biden’s CDC has shown the ability to use a more collaborative process. The agency consulted with dozens of stakeholders, for example, earlier this year before issuing guidance for reopening in-person learning at schools.

Public health experts largely agreed that Walensky was correct in her assessment that vaccines are highly effective in protecting the inoculated.

But in telling the country that it’s okay for vaccinated people to stop wearing masks in most places, they removed the societal pressure to wear face-coverings for all people, increasing the likelihood that some portion of unvaccinated people will also stop wearing masks, public health officials said.

While cases are dropping “really encouragingly,” they are still extremely high, Frieden said.

“In another two to six weeks, we’re going to be in a much better position,” Frieden said. “So I really wish this had not happened, frankly, because this would have allowed us to stay a little safer for a little longer.”

Others argued that the CDC should have tied lifting mask mandates to lower community spread and high vaccination rates, giving states and cities a sense of when it would make sense to get rid of face coverings.

The CDC did say that all Americans should remain masked in some settings, like public transit and hospitals. But the guidance was too roughly drawn, according to some public health experts, who said they believed masking should still be required in any essential business such as grocery stores.

Some defenders of the administration and Walensky noted she is taking over the agency at an extraordinarily difficult time. She came in the middle of a pandemic response with a new administration, when the CDC is front and center and its actions are under intense scrutiny. She also has not worked in government before or overseen a large organization.

“They’re making a lot of changes at the CDC simultaneously,” said Emanuel, noting that two top staff members are leaving. “I think there’s a big effort to reform the CDC while trying to fly the airplane and sometimes that leads to . . . non-optimal rollouts of decisions,” he said.

The larger takeaway for some public health experts is that Biden should consider a more nuanced approach to policymaking.

“Scientific evidence rarely, if ever, points to a single policy outcome,” said Jason L. Schwartz, an assistant professor of health policy at the Yale School of Public Health. “But instead, it’s got to be interpreted in light of what we know, what we don’t fully understand, and then what the consequences — and especially the unintended consequence — might be.”