As a wave of at-home tests for coronavirus are coming on the market, federal regulators issued stern guidance saying that none of them has yet been approved for use and warning consumers to be wary of “unauthorized fraudulent test kits.”

Hours after STAT reported on Friday that at least four startups would roll out at-home tests over the next week, the Food and Drug Administration released a statement saying: “We want to alert the American public that, at this time, the FDA has not authorized any test that is available to purchase for testing yourself at home for Covid-19.”