Health officials said on Tuesday that the United States is "running out of money" to fight COVID-19, as more than 80 million cases have been reported in the country.

"The federal government is running out of funds to provide Americans, especially those who are uninsured, with COVID-19 vaccines, tests and treatments," stated an op-ed for The New York Times co-authored by US Surgeon General Vivek Murthy and David Kessler, chief science officer for the COVID-19 Response Team.

Federal funding to cover the cost of COVID-19 testing and treatment for uninsured people reportedly dried up this week. Several testing providers will no longer provide tests for free to the uninsured, saying they will begin to charge between $100 and $195 for PCR tests, reported ABC News.

In addition, the federal government cut shipments of lifesaving monoclonal antibodies last week to states by 35 percent. Officials anticipate running out of monoclonal antibodies later this spring.

This comes as the total number of COVID-19 cases in the US hit the 80 million milestone on Tuesday afternoon, with more than 978,000 related deaths, according to data from Johns Hopkins University. Both figures are the highest in the world.

The national public health agency said on Tuesday that subvariant BA.2 was estimated to account for more than half of the coronavirus variants in the country.

Scientists believe BA.2 is more transmissible than the original Omicron strain, though it is not believed to cause more severe COVID-19.

The hardest-hit region is the Northeast, where the variant represents more than 70 percent of sequenced cases in New York and New Jersey, according to the Centers for Disease Control and Prevention.

BA.2 has doubled as a proportion of circulating variants in the US about every two weeks. At the beginning of February, the Omicron subvariant made up just 1 percent of sequenced coronavirus cases in the US.

Nationally, the seven-day average of newly reported cases remained around 30,000 for about two weeks, according to Johns Hopkins University data.

Second booster shots

Signs of a resurgence came after dozens of states moved to close public testing sites. Case data have become less reliable with more people using at-home COVID-19 tests, of which the results are generally not reported to officials. Experts said infection totals are likely significantly undercounted.

The Food and Drug Administration authorized second booster shots－or the fourth doses－of the Pfizer-BioNTech and Moderna COVID-19 vaccines on Tuesday for people aged 50 and older. The agency said those who are eligible can get the additional shot at least four months after their previous booster.

The FDA also authorized a second booster for those aged 12 and older who have severely weakened immune systems, with the same time interval between boosters.

The decision means that tens of millions of people in the US are now eligible for another shot.

The CDC is expected to issue advice on who should consider getting the shot.

But the second booster is only for higher risk groups, FDA vaccine chief Peter Marks said, because there is evidence that protection can wane and the FDA decided the option "will help save lives and prevent severe outcomes".

There is limited evidence on how much benefit another booster could offer right now. The FDA made the decision without input from its independent panel of experts, which has been grappling with how much data is needed to expand shots, reported The Associated Press.

"At some point, we're going to have to realize that this is a virus that's going to be with us and that we have to come to grips with dealing with it on a regular basis," Marks said.

Xinhua and agencies contributed to this story.