FOSTER CITY (KPIX 5) — Bay Area biotech company Gilead Sciences is in the spotlight after the firm’s drug remdesivir got positive results in a trial treatment on COVID-19 patients.

But some experts are not celebrating yet.

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Researchers at the University of Chicago conducted a trial on the Foster City based company’s drug remdesivir with 125 coronavirus patients, most of whom were severely ill.

While two patients died, health-care publication Stat News reports that most patients improved so quickly they were discharged in less than a week.

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Despite the encouraging news, UCSF COVID-19 Researcher Dr. Carolyn Calfee is urging caution about any experimental therapy.

“I think it offers potential hope, and I think we have to be looking as aggressively as we can to find new therapies. But I think we also have to be careful to not conclude that because someone has gotten a particular drug and had a good outcome, that it means the drug was responsible for that outcome,” said Dr. Calfee. “They may have had a good outcome regardless of whether or not they got the drug. And that’s why we need to use scientific methods to study these types of interventions.”

With U.S. Health officials cautioning that a vaccine is 12 months away at best, quickly finding an effective treatment for the virus is critical.

Investors clearly liked what they heard from the report. Shares of Gilead Sciences spiked by more than 16 percent in after-hours trading.

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Gilead intends to enroll 4,000 patients in its own trials. So far, the company has offered no comment in regard to the results revealed Thursday.