More than 27 million Americans fully vaccinated against the coronavirus will have to keep waiting for guidance from federal health officials for what they should and shouldn’t do.

The Biden administration said today it’s focused on getting the guidance right and accommodating emerging science, but the delays add to the uncertainty around bringing about an end to the pandemic as the nation’s virus fatigue grows.

“These are complex issues and the science is rapidly evolving,” Centers for Disease Control and Prevention Director Dr. Rochelle Walensky said today. “We are making sure and taking time to get this right and we will be releasing this guidance soon.”

Such guidance would address a flood of questions coming in from people who have been fully vaccinated against COVID-19: Do I still have to wear a mask? Can I go to a bar now? Can I finally see my grandchildren?

The need has slowly grown since January, when the first Americans began to complete the two-dose series of COVID-19 vaccines then available. Now, more than half of people 65 and older have received at least one shot, according to Andy Slavitt, a senior administration adviser on the pandemic.

In Washington state, Raul Espinoza Gomez has 22 grandchildren and great-grandchildren and an appointment Saturday for his second dose of coronavirus vaccine.

By Easter, the 77-year-old’s immune system will be ready to protect him from the virus. But how the family celebrates will depend on government advice, said Melissa Espinoza, 47, of Carnation, Washington, who plans to drive Gomez, her father-in-law, to get his second shot.

“We didn’t gather together as a big family at Christmas,” she said. “We go by what the state and federal guidelines recommend. We’ve had family members adversely affected by COVID. We know the risks are severe.”

Worried about persistently high case loads and deaths, the Biden administration has condemned efforts to relax states’ virus restrictions and pleaded with the public for several months more patience.

The caution has drawn critics, who point to the administration’s own warnings that “fatigue is winning” as evidence that they need to be more optimistic about the path ahead to secure the cooperation of those who are yet to be vaccinated.

“I think it’s going to be overly proscriptive and conservative and that’s the wrong message,” former FDA Commissioner Scott Gottlieb told CNBC Wednesday of the forthcoming CDC guidance. “If we continue to be very proscriptive and not give people a realistic vision for what a better future is going to look like, they’re going to start to ignore the public health guidance.”

Dr. Jeremy Faust, an emergency physician at Brigham and Women’s Hospital in the Division of Health Policy and Public Health, encouraged the CDC to be clearer about when and how it plans to produce guidelines for the vaccinated.

“Making the decision to go by the science is also making the decision that you’re going to have to make a decision, which is really difficult when the science isn’t settled,” he told the AP. “They’re drinking from a firehose of science, and sometimes, it gets messy.”

More than 54 million Americans have received at least one dose of vaccine, and slightly more than half — nearly 28 million — have gotten the recommended two doses. The single-dose Johnson & Johnson shot soon will add a couple million more Americans with questions about what new freedoms they can safely enjoy.

“I do hope I get to see my great-grandchildren more,” said Rolando Solar, 92, who received his second dose in Miami Wednesday. “But I know things will not go back to normal and, for an old man like me, this is as good as it will be.”

Tami Katz-Freiman, 65, of Miami, got her second dose three weeks ago, and plans to watch the Miami Film Festival virtually Sunday at the home of unvaccinated friends. All will wear masks.

“We didn’t have to discuss it with each other, because it’s very clear to me that when there is a doubt and you don’t have a CDC straightforward rule you better be on the safe side and take care for yourself,” Katz-Freiman said.

Three weeks ago, the CDC announced that fully vaccinated people do not have to go into quarantine if they have contact with someone with a confirmed infection (for 90 days after the final shot). But the agency said nothing beyond that, noted Dr. Leana Wen, an emergency physician and public health professor at George Washington University.

“That (quarantine guidance) seems to imply to me that your chance of contracting COVID-19 and being a carrier to others is pretty low,” said Wen, who previously ran Baltimore’s health department.

“(But) we need to focus on what is most relevant to people’s lives, and my patients are not coming in and asking me: ‘If I’m vaccinated, do I still need to quarantine if I’m exposed?’” she continued.

“I’d say the most common question I get is ‘Can I visit my grandchildren?’” Wen said.

Experts say it’s understandable that the CDC has been cautious when many scientific questions remain, including how long vaccine-induced immunity lasts, and whether vaccinated people are still able to transmit the virus to others. The answers are important when advising someone what kind of risk they face in different settings, and how much of a risk they are to others.

“The vaccines at their best, in the clinical trials, were 95% effective, I didn’t say 100%. And that’s why we have to keep wearing masks most of the time,” said Dr. William Schaffner, an infectious-diseases expert at Vanderbilt University.

But CDC has needed to come out with something more for vaccinated people than sticking with the same old mask wearing, social distancing guidance, he added.

“People are so eager to do something and they want to see some tangible benefit from the vaccines. Americans are impatient. They want to get on with it,” Schaffner said.

Indeed, “there is a real cost to putting off this guidance,” as people turn to their own doctors for advice, or just make their own assumptions and decisions, Wen said.

Waiting too long can diminish the agency’s relevance on this kind of matter, said Wen, who believes CDC should have had some kind of guidance in place for vaccinated people back in January.

Clearly, vaccinated people should have been encouraged to go get cancer screenings, dental care, or other needed medical appointments. CDC officials also could have said that it’s OK for small groups of fully vaccinated people — maybe two or three couples, for example — to gather together for a dinner or other small gathering, she said.

Regarding small gatherings among people who have been fully vaccinated, “the relative risk is so low that you would not have to wear a mask, that you could have a good social gathering within the home,” said Dr. Anthony Fauci, the government’s leading infectious diseases doctor, during a recent White House briefing.

Some experts discussed the possibility that movie theaters or cruise ships or certain other businesses might open up to vaccinated people, and ask for proof of vaccination status. Israel’s government has begun issuing a “green pass” vaccination certificate to anyone who has received two doses of COVID vaccine through an accredited vaccination service.

“I don’t know if in this country we would tolerate the federal government issue some kind of pass, the way they did in Israel,” Wen said. But businesses might want such passes and they would be an incentive that might help the overall rate of vaccination, Wen said.

The only incentive Espinoza’s family needed for vaccination was seeing her and her husband hospitalized with COVID-19 this winter. Still recovering, she uses oxygen at home.

Vaccination of the family elders means one step closer to returning to traditions they love: Church on Palm Sunday and, a week later, an Easter egg hunt for the kids and a meal featuring slow-cooked barbacoa, a Mexican beef dish.

“I hope people will stay home and stay safe as much as possible until we can all get vaccinated and eradicate this disease,” Espinoza said.