COVID-19 patients who took the antiviral remdesivir recovered about 30 percent faster than those on a placebo, the results of a major clinical trial showed Wednesday, as the top US epidemiologist hailed the drug's "clear-cut" benefit.
The finding represents the first time any medication has been shown to improve outcomes against the COVID-19 illness, which has claimed more than 220,000 lives globally and ground the world economy to a halt.
The US National Institute of Allergy and Infectious Diseases (NIAID), which oversaw the trial, said that patients on the drug made by Gilead Sciences had a 31 percent faster time to recovery than those on a placebo.
"Specifically, the median time to recovery was 11 days for patients treated with remdesivir compared with 15 days for those who received placebo," it said.
For Anthony Fauci, who leads the NIAID and has been one of the government's point people during the crisis, "the data shows that remdesivir has a clear-cut, significant, positive effect in diminishing the time to recovery."
"Although a 31 percent improvement doesn't seem like a knockout 100 percent, it is a very important proof of concept because what it has proven is that a drug can block this virus," he told reporters at the White House.
The results also suggested that people who were on the drug were less likely to die, although the difference was small. The mortality rate was 8.0 percent for the group receiving remdesivir versus 11.6 percent for the placebo group.
The trial began on February 21 and involved 1,063 people across 68 locations in the United States, Europe and Asia.
Neither the patients nor their physicians were aware of which group they belonged to, in order to eliminate unconscious bias.
Peter Horby, an epidemiologist at the University of Oxford who was not involved in the study, said: "We need to see the full results, but if confirmed this would be a fantastic result and great news for the fight against COVID-19."
The CEO of Gilead Sciences, the US laboratory that manufactures remdesivir, Daniel O'Day, said the company plans to donate the 1.5 million doses they have in stock -- enough to treat at least 140,000 patients.
The company would then sell the drug at an "affordable" price, he told the health news site Stat.
Remdesivir, which previously failed in trials against Ebola, belongs to a class of drugs that act on the virus directly -- as opposed to controlling the abnormal and often lethal autoimmune response it causes.
It mimics one of the four building blocks of RNA and DNA and gets absorbed into the virus's genome, short-circuiting its replication process.
In his remarks to the press, Fauci indicated that the approach could pave the way for better drugs adopting the same model.
While the findings were broadly welcomed by scientists, some cautioned that the benefits were relatively modest.
"This is the first evidence that remdesivir has genuine benefits, but they are certainly not dramatic," said Stephen Evans, a medical statistics expert at the London School of Hygiene and Tropical Medicine.
"These data are promising, and given that we have no proven treatments yet for COVID, it may well lead to fast-track approval of remdesivir," said Babak Javid, principal investigator at Tsinghua University School of Medicine in Beijing.
"However, it also shows that remdesivir is not a magic bullet."
There had been mixed news about the intravenous antiviral in recent weeks.
A summary of results posted on the website of the World Health Organization last week showed it failed in a smaller Chinese trial. The Lancet on Wednesday published the formal paper describing that experiment.
In that study of 237 patients in Wuhan, doctors found no positive effects of administering the drug compared with a control group of adults, except for those patients who required ventilators.
But the Chinese test had to be halted early because it could not recruit enough people, and was considered by many experts to be too small to be reliable.
Fauci said it was "not an adequate study."
Apart from remdesivir, the antimalarial drugs hydroxychloroquine and chloroquine are also being widely used against COVID-19 on a so-called "compassionate basis" pending results from large trials.
Other therapies that are being studied include collecting antibodies from COVID-19 survivors and injecting them in patients, or harvesting antibodies from genetically engineered mice that were deliberately infected.