Facing a slower-than-hoped coronavirus vaccine rollout, the Trump administration abruptly shifted gears to speed the delivery of shots to more people. The move came as cases and deaths surged to alarming new highs.

Health and Human Services Secretary Alex Azar announced a series of major changes to increase supply of vaccines, extend eligibility to more seniors and provide more locations for people to get shots. Administration officials describing the new policies conveyed a notable sense of urgency.

One change will have some teeth to it. Azar said going forward the federal government will base each state's allocation of vaccines partly on how successful states have been in administering those already provided.

“If you are not using vaccines that you have the right to, then we should be rebalancing to states that are using that vaccine," Azar said at news conference on Tuesday.

That won't happen overnight, not until officials try to sort out whether lags in reporting could be the reason for what appears to be subpar performance.

Currently, the government allocates vaccines based on state population.

Azar also said the government will stop holding back the required second doses of the Pfizer-BioNTech and Moderna vaccines, practically doubling supply.

Both those shots require two doses to achieve optimum protection.

Additionally, Washington is urging states to immediately start vaccinating other groups lower down the priority scale, including people age 65 and older and younger people with certain health problems.

The move to increase the supply of vaccines better aligns the outgoing administration with the new Biden-Harris team. On Friday, President-elect Joe Biden said he will rapidly release most available vaccine doses to protect more people. He said he supported immediately releasing vaccines that health authorities were holding back out of caution, to guarantee they would be available for people needing their second dose.

“This next phase reflects the urgency of the situation,” said Azar. “Every vaccine dose sitting in a warehouse rather than going into an arm could mean one more death that could have been avoided."

Initially the government had been holding back second doses as a safety precaution against potential shortfalls in production. Now, officials say they are confident the needed supply will be there. And people needing a second dose will have priority.

“This is not a supply issue at this moment in time,” Vice President Mike Pence told governors on a White House call. A recording was provided to The Associated Press.

Azar also gave states the green light to designate more places where people can get shots. Those locations can include tens of thousands of pharmacies, federally supported community health centres that serve low-income communities, and mass vaccination sites already being set up in some states.

The flurry of changes raised questions for some local officials, still trying to get vaccination campaigns into full swing.

As of Monday morning, the government had distributed about 27.7 million doses to states, US territories and major cities. But only about 9.3 million people had received their first shot, according to the Centers for Disease Control and Prevention's online tracker. That means only about 34 per cent of the available vaccines had been administered.

Initially, the shots were going to health care workers and nursing home residents. Those 75 and older were next in line. But problems arose even in vaccinating that limited pool of people. Some hospital and nursing home workers have been hesitant to get the vaccine. Scheduling issues created delays in getting shots to nursing homes.

Biden, who has been highly critical of the Trump administration's pandemic response, is expected to give a speech Thursday outlining his plans. He's looking for a turnabout in his first 100 days.

Azar said they'll brief the Biden transition team on the changes, but didn't seek their blessing.