The antiviral drug remdesivir was fast-tracked by the Food and Drug Administration after preliminary results found it shorted recovery times for patients hospitalized with COVID-19. But one doctor participating in the study said he has “hope and optimism” the data will ultimately show the drug saves lives, too.

“The data so far has showed a trend toward … improvement in survival. However, it did not reach statistical significance. That, though, may change, as more data come in,” said Dr. Babafemi Taiwo, the chief of infectious diseases at Northwestern Medicine — one of many institutions participating in the government-run study.

The National Institutes of Health released the preliminary results last week, which indicated patients on remdesivir recovered more than 30% faster than the placebo group. The study also suggested a survival benefit — with a mortality rate more than 3% lower for patients on the drug — but as Taiwo explained, researchers need more information before they can say with certainty.

“We cannot make that kind of statement until the study is complete and we have the full data reported,” he said.

Taiwo told Jim Braude on WGBH News’ Greater Boston Monday that he’s “very encouraged” by how quickly the federal government has moved to get the experimental treatment to patients who need it.

“It allows doctors to use a drug that may improve the outcomes for many of our patients. The alternative is to wait for the approval to go through the normal process, which will take much, much longer,” he explained.

Gilead Sciences, the pharmaceutical company that produces remdesivir, said it will donate 1.5 million doses of the drug — which will be distributed by the federal government. The donation could treat as many as 140,000 patients and the company said, by the end of the year, they plan to produce enough doses to treat 1 million more.

Taiwo pushed back on the results of a second remdesivir trial conducted in Wuhan China, the first epicenter of the coronavirus pandemic, which found the drug had no impact on the disease at all.

“The results from Wuhan has to be taken in proper context. That study intended to enroll over 400 participants but ended up enrolling just over 250,” he said. “The inability to show a difference in that study cannot be taken to mean a lack of difference.”

Remdesivir is one of a number of experimental coronavirus treatments undergoing clinical trials, but Taiwo said nothing else has come so far, so quickly.

“There are other compounds that are being looked at. But in terms of something that will be available at same pace we’ve seen for remdesivir — I think that it takes a lot of people, and a lot of work, and a lot of well-meaning volunteers — so there’s nothing within a matter of weeks or a month will be in our hands,” he said.

Taiwo said he is also hopeful about the timeline of a coronavirus vaccine, which President Donald Trump has said will be ready by the end of the year.

“A lot of people are working very hard, not just in the United States, but also internationally. … There is a unique pipeline that includes, not one but many agents being tested at the same time,” Taiwo explained. “I hope the president is right because that would be the best-case scenario for our patients and for our community and country as a whole.”