Remdesivir is a novel antiviral adenosine nucleotide analog that has been under development by Gilead as a treatment for Ebola. The company shifted the drug's focus to COVID-19 after finding that it has antiviral properties against other RNA viruses, such as SARS-CoV-2, which causes the COVID-19 respiratory disease.

Gilead had applied for orphan drug status for remdesivir, and the FDA approved the designation on March 23. But a backlash quickly developed, as the designation could potentially keep lower-priced generic versions of the COVID-19 treatment off the market for several years. Gilead requested a withdrawal of the application on March 25.

To qualify for orphan designation, drug manufacturers must show that their product will treat a population of fewer than 200,000 patients or that it would be unprofitable. The Orphan Drug Act, passed in 1983, offers significant tax credits for qualified clinical trials and waives fees that companies pay to have their marketing applications reviewed by the FDA. It also offers approved drugs market exclusivity for seven years; new drug molecules typically only get five years of this exclusivity.

With well over 69,000 COVID-19 cases in the U.S. as of March 26, and an increasing number of cases each day, the number of patients in the U.S. will inevitably surpass the 200,000 ceiling below which drugs are eligible for orphan status. Moreover, given the delay in diagnostic testing for COVID-19, the actual number of cases is most likely much higher than the number of confirmed cases. At the time of Gilead's submission, the FDA noted that remdesivir met all the qualifications for the orphan drug designation.

But after the FDA's decision became public, opposition to the move was soon voiced by a number of organizations, including Public Citizen and the AIDS Healthcare Foundation, calling for the withdrawal of orphan drug status for remdesivir.

Adding impetus to the calls was the fact that research on remdesivir was financed in large part by the U.S. Centers for Disease Control and Prevention (CDC), the U.S. National Institutes of Health (NIH), and the U.S. Army, among other global public health agencies. The organizations claim that Gilead is using publicly funded research to gain an exclusive orphan drug monopoly guarantee for their product. They called for Gilead to relinquish its claims immediately.

More criticism of the FDA's decision was seen on social media. In a March 24 statement, Senator Bernie Sanders (D-VT) stated that the FDA was "exploiting a law reserved for rare diseases."

Gilead bowed to the pressure on March 25, releasing a statement saying that it has rescinded the orphan drug designation for remdesivir. The company said it was confident that it could maintain the urgent development timelines for the treatment, even without the designation.