The drug maker Gilead Sciences is expanding its clinical trials of the antiviral drug remdesivir as a possible coronavirus treatment into several countries outside China, the company announced on Wednesday.
Two new clinical trials of remdesivir are to begin in March, involving “approximately 1,000 patients at medical centers primarily across Asian countries, as well as other countries globally with high numbers of diagnosed cases,” Gilead said in a statement. It did not specify the countries where the trials will take place.
Remdesivir is already being tested in Wuhan, China, the center of the epidemic, and the United States National Institutes of Health announced on Tuesday that the drug would also be studied in some of the patients who contracted the illness overseas and were now being treated in Nebraska.
Results from the trials in Wuhan are expected in April, the company said.
The drug is still experimental, not yet approved to treat any disease. There are no approved treatments for illnesses caused by coronaviruses, including the new one, known as Covid-19. Studies of infected mice and monkeys have suggested that remdesivir can fight coronaviruses, and it appeared to cause few side effects when it was tested in patients with Ebola, although it did not work well against that virus.
The experimental drug also stirred interest after doctors administered it to the first coronavirus patient in the United States. The man was hospitalized in Washington State, and his symptoms seemed to improve. But the experience of one patient cannot be used to determine whether any drug works.
Several companies are also working to develop a vaccine for the virus, which has spread around the globe. The number of cases now exceeds 80,980, and deaths total nearly 3,000.
One of the companies, Moderna, said Monday it had delivered its experimental vaccine to the N.I.H. for early testing in humans, a record-setting pace. The nation’s top health officials have cautioned that development of a vaccine to treat large populations might take a year or more.
Researchers are trying to determine which patients remdesivir might help most, by giving the drug to people who are severely ill and also some who are not as sick. They also hope to find out how long a course of treatment is needed.
“Because it’s an outbreak and we try to target people who stand to have a clear benefit, first we target people who are symptomatic, so they are hospitalized,” Dr. Diana Brainard, Gilead’s senior vice president for H.I.V. and emerging viruses, said in an interview. “There is a precedent in respiratory viral infections, that the earlier you treat, the better, and there may be a threshold beyond which it doesn’t make sense to treat.”
On the other hand, she said, if the drug does help severely ill patients, that could be its greatest impact.
Another goal of the new trial is to find out if a shorter course of treatment will work. If a shorter duration does work, she said, “that automatically doubles the drug supply.” Faster treatment would also get patients out of the hospital faster, lessen their exposure to hospital-based infections and make room for more patients, she added.
“We are looking for ways we can help the world prepare as well as possible for what appears to be a pandemic at this point,” Dr. Brainard said.
One of the new trials will include 400 severely ill patients, who will be picked at random to receive either five days or 10 days of treatment with the drug, which must be given intravenously.
The other trial will involve 600 moderately ill patients. Along with standard care — oxygen if needed, fluids, medicines for pain and fever — a third will receive the drug for five days, and a third for 10 days. The last third will receive standard care alone.
In the last month, Gilead’s stock has risen 17 percent, to $74.70 at the close of markets Wednesday from $68.80 in late January.