WASHINGTON — U.S. regulators last week allowed emergency use of the first drug that appears to help some COVID-19 patients recover faster, a milestone in the global search for effective therapies against the coronavirus.


The Food and Drug Administration cleared Gilead Sciences’ intravenous drug for hospitalized patients with “severe disease,” such as those experiencing breathing problems requiring supplemental oxygen or ventilators.


Gilead CEO Daniel O'Day and Food and Drug Administration Commissioner Stephen Hahn attended a White House briefing announcing the approval.


“This was lightning speed in terms of getting something approved,” said Hahn, calling the drug “an important clinical advance.“


The FDA acted after preliminary results from a government-sponsored study showed that the drug, remdesivir, shortened the time to recovery by 31%, or about four days on average, for hospitalized COVID-19 patients.


Those given the drug were able to leave the hospital in 11 days on average vs. 15 days for the comparison group. The drug may also help avert deaths, but that effect is not yet large enough for scientists to know for sure.


Dr. Sameer Khanijo, a critical care specialist, said he wants to see additional studies to clarify the drug's benefit.


“I don’t think this is a cure yet, but I think it's starting to point us in the right direction," said Khanijo of North Shore University Hospital in New York. “As a society it’s nice to have something that will help stem the tide of this disease.”


The FDA said preliminary results from the government study warranted Friday's decision, though regulators acknowledged “there is limited information known about the safety and effectiveness of using remdesivir.”


The drug’s side effects include potential inflammation of the liver and problems related to its infusion, which could lead to nausea, vomiting, sweating and low blood pressure. Information about dosing and potential safety issues will be provided to physicians and patients, the FDA said.


The National Institutes of Health’s Dr. Anthony Fauci said Wednesday the drug would become a new standard of care for severely ill COVID-19 patients. Remdesivir, which blocks an enzyme the virus uses to copy its genetic material, has not been tested on people with milder illness.


The FDA authorized the drug under its emergency powers to quickly speed the availability of experimental drugs, tests and other medical products during public health crises.


Here are some questions and answers about remdesivir.


Q: How much does the drug help?


A: Remdesivir reduced the time patients were in the hospital by 31% to 11 days on average versus 15 days for those just given usual care, preliminary results of the study found.


About 8% of those on the drug died versus 11.6% of the comparison group, but the difference is not large enough for scientists to say for sure that the drug was the reason.


Q: What about folks with milder illness?


A: Remdesivir so far has only been tested in people with moderate to severe illness who were hospitalized and got it through an IV.


Even among those in the study there was "a very big span of illness," from people just needing a little extra oxygen to those requiring breathing machines, said Dr. Elizabeth Hohmann, who enrolled 49 patients in the study at Massachusetts General Hospital.


"We need more information to see how best to use it going forward" and which types of patients get the most benefit, she said.


Q: How much remdesivir is there and what will it cost?


A: Gilead has or is close to having 140,000 treatment courses now and will donate them, Chairman Daniel O'Day said in a letter last week. The company aims to have made a total of 500,000 treatment courses by October and more than 1 million by December.


Gilead’s own testing suggests that five days of treatment are as good as 10, so the estimates of how many people can be treated with the available supply likely can be doubled, he added.