Close-up of the Moderna vaccine at the Park County’s Department of Health’s COVID-19 Vaccination Clinic for Seniors 80+ on January 28, 2021 in Livingston, Montana.

William Campbell | Getty Images

Some health care providers have regularly withheld doses of vaccine for Covid-19 to ensure supplies are in place when people come back to get their second shots, an official on President Joe Biden’s coronavirus response team said Monday.

Andy Slavitt, a senior advisor to Biden’s Covid Response Team who previously served in the Obama administration, said health care providers shouldn’t withhold vaccine doses. He said the practice is actually causing some vendors to cancel appointments and preventing some Americans from getting their first shots.

“We want to make it clear that we understand why health care providers did this, but that it doesn’t have to and shouldn’t,” he told reporters during a coronavirus briefing, adding that US officials are aware of supplies of Covid vaccines to states were often unpredictable during the early rollout in late December.

“We fully understand that this is a direct result of the unpredictability that many states and suppliers have had about the number of doses they would receive,” he said. “That’s one reason we announced last week that the federal government would provide a continuous three-week window for the vaccines to be shipped.”

“With this move, states and vaccine providers will use their allocation of the first doses faster to vaccinate as many people as quickly and equitably as possible because they now have the predictability,” he said, that the second shots will be on time.

Biden is trying to accelerate the pace of vaccination in the US after a slower-than-expected rollout under the administration of former President Donald Trump. The Biden government has advised states and health care providers that they no longer need to withhold the two-dose doses reserved for the second round of Pfizer and Moderna vaccinations.

Still, some states have raised concerns that the federal government will be able to maintain an adequate dose supply for the second round of firing. Pfizer and Moderna vaccines require two vaccinations three to four weeks apart, and the states vaccinate approximately 1 million people daily.

The U.S. has distributed nearly 50 million doses of vaccine, but only about 31.1 million had been administered as of 6 a.m. ET Sunday, according to the Centers for Disease Control and Prevention. As of Monday, states had 62% of their vaccine inventories managed, but officials expect that number will improve, Slavitt said.

U.S. officials also hope vaccine supplies will increase after Johnson & Johnson’s Covid-19 vaccine was approved by the Food and Drug Administration for emergency use. The FDA could give the OK this month.

The Department of Health and Human Services announced in August that it had signed a contract with Janssen, J & J’s pharmaceutical subsidiary, worth approximately $ 1 billion for 100 million doses of its vaccine. The deal gives the federal government the opportunity to order another 200 million cans, according to the announcement.

Unlike Pfizer and Moderna’s vaccines, J & J’s vaccine only requires one dose, which makes logistics easier for healthcare providers.

Dr. Anthony Fauci, the nation’s leading infectious disease expert, said Monday that making sure people who get their first dose can get their second remains a top priority for officials. CDC director Rochelle Walensky said the agency is still recommending people get their second recordings on time.

On Sunday, an epidemiologist advising Biden’s transition to the Covid-19 crisis warned of an impending wave of infections and said the US should adjust its vaccination strategy to save lives.

Dr. Michael Osterholm told NBC’s Meet the Press that the government should try to give as many first vaccine doses as possible, especially for those over 65, before there is a potential increase in cases involving mutations overseas.