More than 82 million COVID vaccine doses went to waste in the U.S. from December 2020 until the middle of May, according to data from the Centers for Disease Control and Prevention, NBC News reported .

The majority of discarded doses came from CVS and Walmart, making up about a quarter of wasted vaccines, mainly due to the large amount they handled.

Five other vaccine providers Health Mart, DaVita, Rite Aid, Publix and Costco threw out a higher proportion of the doses that they received.

States also reported on wasted doses. Among them were Oklahoma, which threw out 28% of the doses it received, and Alaska, which discarded 27% of its share.

As demand for COVID vaccines decreases, it is inevitable there will be waste, the CDC explained .

As the rate of vaccine administration slows, the likelihood of leaving unused doses in a vial may increase, even when providers continue to follow best practices to use every dose possible, the CDC states on its website.

Some waste is attributed to doses reaching their expiration date before they could be administered to patients, while others were ruined due to power outages that took freezers out of use. Unused doses from opened vials that had to be discarded at the end of the day also accounted for some of the waste, according to NBC News .

The U.S. has distributed over 751 million COVID vaccine doses, and administered over 589 million doses. Almost 104 million Americans had received three COVID shots as of Sunday, according to the CDC.

This past week, COVID vaccines were administered at an average rate of 63,456 doses per day, Bloomberg reported .

The news about wasted doses comes as the Biden administration warns the country is short on funds to pay for vaccines, treatments and tests.

Dr. Ashish Jha, the White House COVID-19 response coordinator, said Thursday he is growing increasingly worried the country will be out of vaccines by the fall if Congress doesnt approve COVID funding.

If you want to ask what keeps me awake at night, it is that we are going to run out of vaccines, Jha told reporters. Were not going to be able to have enough of the next generation of vaccines. Were going to run out of treatments. And were going to run out of diagnostic tests, probably in the late fall into winter, if we end up having a significant surge of infections.

We dont have the resources to buy those things. And those purchases need to be made now, Jha continued. They cannot be made in the fall.

The White House said children under five years old could be able to get their first vaccine as early as June 21 .