More than 28 million Americans fully vaccinated against the coronavirus disease 2019 (Covid-19) will have to keep waiting for guidance from federal health officials for what they should and shouldn’t do.

The Biden administration said Friday 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 Friday. “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.”