"That is the most effective way to save lives now", said Department of Health and Human Services (HHS) Secretary Alex Azar during a Tuesday press conference.
"We are going to accept the federal guidance of the 65 plus and the immunocompromised", he said.
"We now believe that our manufacturing is predictable enough that we can ensure second doses are available for people from ongoing production", Azar told ABC's "Good Morning America". Even if those doses can be manufactured and shipped seamlessly, that's only enough for 100 million people, given that the now authorized vaccines require two doses each.
The move to increase the supply of vaccines better aligns the outgoing administration with the new Biden-Harris team.
Last week, a spokesman for President-elect Joe Biden said Biden, who takes office January 20, would release more of the reserved doses.
"This next phase reflects the urgency of the situation", said Azar. Last week, the administration announced that pharmacies enrolled in a government partnership (19 pharmacy chains and associations) could be used to give vaccine shots.
Tom Frieden, former director of the CDC, was among the people who criticized the original decision to hold back the second dose. Now, officials say they are confident the needed supply will be there. And people needing a second dose will have priority.
"Ideally, the push would be to get as many people as you can some immunity and worry about the booster shot later", said Davis.
The flurry of changes raised questions for some local officials, still trying to get their vaccination campaigns into full swing. That means only about 34% of the available vaccines had been administered. Those 75 and older were next in line.
Sommer pointed out that the government has not only failed on a number of levels to vaccinate millions of people, they have also fallen short when deciding who would do the vaccinating and where. Scheduling issues created delays in getting shots to nursing homes. In Florida, Gov. Ron DeSantis opened up vaccinations to people 65 and older.
On Tuesday, he also sought to deflect blame to the states for the slow uptake of vaccines.
"We've already distributed more vaccine than we have health care workers and people in nursing homes", Azar said.
"So everything is now available to our states and our health care providers".
The Trump administration directed a crash effort to develop, manufacture and deliver vaccines, hoping to avoid a repeat of earlier debacles with coronavirus testing.
Each state has its own plan for who should be vaccinated, based on recommendations from the federal Centers for Disease Control and Prevention.
The slow pace of the vaccine rollout has frustrated many Americans at a time when the coronavirus death toll has continued to rise.
Biden intends to join his call for accelerating vaccinations with a pitch for more congressional relief aimed atfunding the effort, according to people familiar with his plans, who spoke on the condition of anonymity because they were not authorized to discuss the matter.
Azar said the pace of vaccinations has picked up, on track to reach 1 million daily within a couple of weeks. He has set a goal for the country to deliver a first shot to 100 million people within his first 100 days in office.
"You gain something and you lose some things", she said.
Letting more groups in line "all of a sudden makes a lot more people potentially eligible and certainly interested and we need to have the systems in place to get them the vaccine", Casalotti added.
But there was an urgency to the statements from administration officials.
"We're in a race against this virus and quite frankly, we're behind", U.S. Surgeon General Jerome Adams told "Fox & Friends".
Biden is expected to give a speech Thursday outlining his plan to speed vaccines to more people in the first part of his administration. Biden already announced last week that he plans on releasing nearly every available dose of the coronavirus vaccine once he takes office, a position that put him in opposition to Trump's previous policy of holding on to half of the vaccines to make sure that second doses are available.
Azar said they'll brief the Biden transition team on the changes, but didn't seek their blessing.