WASHINGTON – The White House is tracking reports of fake vaccination card schemes but remains focused on ramping up vaccinations, press secretary Jen Psaki told reporters Monday.

“We are certainly aware of them. We’ve seen the reports and we, of course, defer to law enforcement and other authorities who are overseeing and cracking down where this has come up,” Psaki said at the daily news briefing, cautioning that she did not have data on whether the fake-card schemes were pervasive.

Adults over age 16 in all 50 states, plus the District of Columbia and Puerto Rico, are eligible for coronavirus vaccines, which are accompanied by a free paper card that allows them to prove that they have been vaccinated.

“The best way to get a vaccine card is to get vaccinated. And that’s what our focus will continue to be,” Psaki said.

More than 131 million people in the United States have received at least one shot of coronavirus vaccine, according to data released by the Centers for Disease Control and Prevention.

The Washington Post reported Sunday that some Americans are making or buying falsified paper vaccination cards to claim that they have gotten shots, particularly as businesses ask for proof of vaccination. The Department of Health and Human Services’ inspector general has said that reports of fake card scams have surged in recent weeks and that they now account for up to half of coronavirus-related whistleblower tips. The FBI and state attorneys general have warned that the practice is illegal and that they would prosecute people in the United States who are found to be making, selling or using fake cards.

Some public health experts have said the rise of fake paper cards has increased the need to adopt digital “vaccine passports” that would better track vaccinations and be harder to counterfeit, though the concept has been criticized by Republicans. The White House has said it will not issue digital passports but work to set guidelines for credentials that are being devised by the private sector.

Law enforcement officials warn that a burgeoning trade in counterfeit coronavirus vaccination cards could spur the spread of the coronavirus even as the United States looks to open up again.

Biden marked the vaccine availability with a video urging Americans to get their shots.

“Folks, I have good news,” Biden said in a White House clip. “Everybody is eligible, as of today, to get the vaccine. We have enough of it; you need to be protected, and you need, in turn, to protect your neighbors and your family. So please, get the vaccine.”

Meanwhile, the nationwide pause in the use of Johnson & Johnson’s single-dose coronavirus vaccine probably will be lifted by Friday, according to Anthony Fauci, the nation’s top infectious-disease expert.

Researchers at Oxford University plan to deliberately reinfect healthy individuals who recovered from covid-19, the illness that can be caused by the novel coronavirus, in a new trial tracking immune response to the virus.

Despite major gains in vaccination, the increase in daily new cases in the United States has been steady for months, with many states showing substantial surges. More than 566,000 people have died of covid-19 in the United States.