As coronavirus antibody tests flood the market, regulators are accusing some sellers of taking advantage of people’s desperation to learn if they’ve already been infected.

In the last two weeks, state and local regulators have issued cease-and-desist orders to people and businesses selling COVID-19 antibody tests in Southern California, Las Vegas, and New Mexico, on the grounds that they were illegally advertising or processing these tests. Health officials in Kansas have also intervened to block a hospital from falsely claiming the tests could diagnose the disease.

The tests, which reveal the presence of antibodies that presumably protect you against reinfection, are being touted as a key tool for reopening the US economy and for identifying just how many people have actually been infected. Almost none of the antibody tests currently available in the US have been verified by the FDA, and health care providers across the country are being forced to choose which tests to offer with very little information about their accuracy.

Many providers are selling manufacturers’ tests with the proper caveats, making it clear to customers that they aren’t FDA-approved and they may not be accurate. But as demand for the tests skyrockets, other sellers are making false claims, leading state and local regulators to play whack-a-mole.

Following a growing number of local reports about misleading claims, the FDA on Tuesday warned health care providers that antibody tests should not be used to diagnose whether someone currently has the virus.

“I think we should expect to see companies continue to pop up selling unproven, and in some cases probably just bad, testing,” Patti Zettler, an assistant law professor at Ohio State University and a former attorney at the FDA, told BuzzFeed News by email. “There’s a market to take advantage of because we all, of course, want testing.”

In Dickinson County, Kansas, an hour west of Topeka, Herington Municipal Hospital has gotten into trouble with health officials for the way it’s been advertising its antibody tests. These tests “will not only tell you if you have the active virus but will also tell you if you have immunity,” the hospital posted on its website and Facebook page last week.

In fact, according to the FDA, no blood antibody tests have been proven capable of telling if a person currently has the virus, unlike nasal- and throat-swab diagnostic tests. Scientists also do not know definitively whether, or for how long, antibodies protect a person from getting reinfected.

County and state health officials in Kansas have asked Herington to stop selling the tests, saying that its claims were causing confusion and leading people to mistakenly believe they were infectious, the Abilene-Reflector Chronicle, a local newspaper, reported Monday.

“They are creating a lot of misinformation in the county and it is having repercussions outside our county,” Brian Holmes, Dickinson County’s health officer, told the paper. The county and the hospital did not return BuzzFeed News’ requests for comment.

Last week on a college campus in Cardiff, California, a drive-thru clinic called the COVID Clinic was ordered to stop operating by San Diego County. The county health agency said it failed to provide “necessary credentials and certifications required by State law in order to conduct the tests” and therefore “may not be producing reliable and verifiable results.”

The COVID Clinic has updated its website to say it was offering tests in Orange County. Matthew Abinante, a physician behind the clinic, did not return a request for comment. The California Department of Public Health did not respond to a request for comment about whether they could operate elsewhere in the state.

Also last week, the Nevada Department of Health and Human Services issued a cease-and-desist order to Sahara West Urgent Care & Wellness in Las Vegas for allegedly operating an “unlicensed laboratory.” It was also reportedly selling antibody tests with the false claim that they could test for a current infection.

The state agency noted in a press release that such “tests are not to be used for diagnostic purposes” and that any antibody test sold by the clinic “would not have a definitive result for the purposes of diagnosing COVID-19.”

A Sahara West representative expressed frustration to the Las Vegas Review-Journal, claiming that it had sought the state’s guidance early on. “We haven’t got much help or clarity from anyone,” spokesperson Andrew Mann said. “And now they’re telling us to stop.” The clinic did not return a request for comment.

And earlier this month, the New Mexico Attorney General issued a cease-and-desist to a woman, Chelsie McGuire, who was using Facebook to advertise COVID-19 antibody tests that she allegedly claimed could produce results in 10 minutes. McGuire was ordered to stop advertisements that make “scientifically unfounded claims” about coronavirus testing, the attorney general said in its notice to her, which also noted that she was not on the state’s list of testing sites. McGuire declined to comment to BuzzFeed News.

At the same time, it’s not always clear, for sellers or consumers, which of these tests can be relied on.

There are now over 110 antibody tests that the FDA has allowed to go to market without having their accuracy claims verified by the agency, part of an effort to quickly increase the number of tests available during the crisis. Only four companies’ tests have received official “emergency use authorization” from the FDA, indicating that their accuracy claims have been independently checked by the agency.

While the FDA is currently choosing to allow most antibody tests to go to market without any federal verification, states might have their own certification requirements or take action under general laws meant to prohibit deceptive business practices. “This means requirements may differ from state to state - and we might for that reason expect to see some variation,” Zettler said.

All those factors make it easier for companies with dishonest claims or credentials to try to capitalize on the moment. As the virus continues to spread, more bad actors will likely emerge and hamper badly needed attempts to bring the pandemic under control, said Steven Joffe, a bioethicist at the University of Pennsylvania.

“To get past this crisis, at least until we have a vaccine or highly effective treatments, we are going to need widespread testing,” Joffe said by email. “But for widespread testing to work, the public is going to have to trust in that testing. Particularly at this moment of threat and division, public trust is a fragile thing. Scammers are going to make it impossible to achieve.”