More than 60% of a group of severely ill COVID-19 patients showed improvement when treated with remdesivir, an antiviral drug currently being tested in several studies globally.
The preliminary results published in the New England Journal of Medicine did not have a control group, meaning that more research is required to better determine if the drug could help sick coronavirus patients.
Nonetheless, 36 of the 53 patients treated with the drug or 68% of the group showed improvement.
The patients in the US, Italy, France, Austria, Spain, the Netherlands, Germany, Japan, and Canada received the drug intravenously for at least ten days.
Seventeen of 30 patients treated with the drug while requiring mechanical ventilation improved. Eight patients saw a worsening of disease. A total of seven patients, or 13%, died.
The differences in outcome could also be due to differences in hospitals and supportive care but the doctors who wrote the study concluded that the drug could be helpful in cases of severe COVID-19 illness.
There have been 1.7 million confirmed cases of COVID-19 and more than 100,000 people have died but there is currently no existing treatment for the virus that caused a global pandemic.
"Although data from several ongoing randomised, controlled trials will soon provide more informative evidence regarding the safety and efficacy of remdesivir for Covid-19, the outcomes observed in this compassionate-use program are the best currently available data," the doctors wrote in the study published on Friday.
Remdesivir included in major COVID-19 drug trials
The drug interferes with an enzyme that helps RNA viruses to replicate and has been shown to be successful against coronaviruses in laboratory studies.
It was initially developed to help treat Ebola during the outbreak in West Africa.
There are several major global studies of the drug which is manufactured by Gilead Sciences in the United States.
The company has already made the drug available for use to more than 1,000 very ill patients with coronavirus and funded the study of 53 patients.
The U.S. National Institutes of Health is currently funding a double-blind study of 440 patients with a control group for the drug.
Remdesivir is also one of several antivirals being tested in the European clinical "Discovery" study which is looking at experimental treatments deemed priorities by the World Heath Organisation (WHO).
That trial is also looking at the drug hydrochloroquine which caused a certain frenzy over its supposed benefits in treating COVID-19 despite few reliable studies of the drug's effects.
More comprehensive results from studies of these drugs are expected next month.