Since the beginning of March, the Food and Drug Administration has granted emergency use authorization (EUA) to dozens of products believed to diagnose or treat COVID-19.

The agency has authorized only four therapies: drugs hydroxychloroquine, chloroquine and remdesivir, along with other treatments like convalescent plasma and hyperimmune globulin, a biologic created from convalescent plasma.

The FDA has also granted dozens of EUAs for coronavirus tests, both diagnostic and antibody (or serology) tests, and for medical device manufacturers attempting to meet demand for the surge in medical equipment use.

The emergency use authorization is a pathway meant to help combat public health emergencies by quickly allowing the use of unapproved products to diagnose or treat an illness.

According to the Food, Drug and Cosmetic Act, products must meet several criteria to receive EUA. Federal officials must decide if the known scientific evidence for the product, including data from clinical trials, shows that the product can treat, diagnose or prevent an illness; the known benefits of the product must also outweigh the known and potential risks of using it; and there must be no approved product or alternative to treat the disease.

The authorization is also intended to last until the public health emergency is officially ended, according to the FD&C Act.

The EUA also requires manufacturers to make fact sheets available to doctors and patients with information like dosing instructions, potential side effects and drug interactions, meant to supplement the drug’s existing labelling.

The FDA also issued an additional emergency use guidance specific to coronavirus earlier this year. That guidance outlines policies for manufacturers and laboratories to increase testing capacity.

The most recent EUA was for Gilead’s remdesivir. That authorization shows just how quickly the FDA is working to get these potential treatments on the market; just two days after the first clinical trial of remdesivir reported results, the FDA granted its emergency use.

“FDA’s emergency authorization of remdesivir, two days after the National Institutes of Health’s clinical trial showed promising results, is a significant step forward in battling COVID-19 and another example of the Trump Administration moving as quickly as possible to use science to save lives,” said HHS Secretary Alex Azar in a statement.

The issue with that speed, however, was illustrated by antimalarial drugs hydroxychloroquine and chloroquine in coronavirus patients. Initially, the drugs showed promising results in early clinical trials, but as more data came in the risks began to increase.

The two drugs were granted EUA on March 28. Four weeks later, on April 24, the agency warned that the drugs may cause serious heart rhythm problems in COVID-19 patients and advised that its use be limited to clinical trials or certain hospitalized patients.