As researchers race to find treatments for COVID-19, a new report appears to show that patients with severe symptoms who are participating in clinical trials at University of Chicago Medicine have responded to a promising antiviral drug.

The early findings were detailed in a video obtained by Stat News that shows Kathleen Mullane, an infectious disease specialist helming the studies at U. of C., telling fellow faculty members that patients with fevers and respiratory symptoms had recovered quickly after being treated with Remdesivir.

As part of the trials at U. of C., 125 COVID-19 patients were treated with Remdesivir, 113 of whom had severe symptoms. Two of them have died, according to Mullane.

In the video, Mullane says most patients were being discharged from the hospital in less than a week. That’s notable because the study is investigating both five- and 10-day courses of the drug.

“Most of our patients are severe and most of them are leaving at six days, so that tells us duration of therapy doesn’t have to be 10 days. We have very few that went out to 10 days, maybe three,” Mullane said.

However, analyzing results of the study could be complicated by the fact the study has no control group and no one in the severe trial was given a placebo to compare results.

Dr. Stephen Weber, U. of C.’s chief medical officer, declined to comment Thursday on how patients in the trials were responding to Remdesivir, which is being scrutinized in a series of studies.

“We don’t have any confirmed results or experience to really speak to with that,” Weber said on a call with reporters.

In a statement Friday, UChicago Medicine warned that “partial data” from and ongoing study should not be used to draw conclusions about the safety or effectiveness of the drug.

“In this case, information from an internal forum for research colleagues concerning work in progress was released without authorization. Drawing any conclusions at this point is premature and scientifically unsound,” the university said in a statement.

Both Northwestern University and University of Illinois at Chicago have also launched trials of Remdesivir, which was developed by Gilead Sciences as a treatment for the Ebola and Marburg viruses. Those trials are both sponsored by the National Institutes of Health and are controlled, meaning that the effectiveness of the drug is compared to patients who received a placebo instead. Researchers also don’t know who gets which, helping to eliminate bias in the study.

“Everyone is waiting on the NIH trial results ... because it’s a controlled trial, which will really give us the answer about whether it’s an effective drug or not,” said Dr. Richard Novak, chief of infectious disease at UIC.

The study for the NIH that UIC and other hospitals are conducting will end this weekend with results likely to be released in mid-May, Novak said.

He said the fact NIH didn’t halt the trial at UIC early may be a good sign, because the trial would have been stopped only if the drug is toxic and hurting people or if there was no indication that the drug was working. However, it also likely means the drug wasn’t so effective that the study was stopped early so it could be given to anyyone.

“I’m hopeful,” Novak said of the comments made about U. of C.’s results so far. “It’s a comment by one person at one study site, and [Mullane] might be right, I hope she is, but we just don’t know that.”

The first analysis of Remdesivir treatment, published earlier this month in the New England Journal of Medicine, showed that more than half of the severely ill patients given the drug saw their conditions improve, though there was no comparison group.

For now, the early results offer a window into the research but no definitive findings on the drug’s efficacy.

“I think it drives all of us a little bit crazy because we’re eager to see results, but we’re hopeful that we’ll see a really positive effect because we want all the help and all the tools that we can have to help fight this infection,” said Weber.