Gilead Sciences Inc., the US company that developed the drug, said the findings appeared inconsistent with evidence from other studies validating the clinical benefit of remdesivir, which was used to treat US President Donald Trump's coronavirus infection.
The Solidarity Trial is the world's largest randomized controlled trial of Covid-19 therapeutics, involving nearly 13,000 patients in 500 hospitals in 30 countries.
Earlier this month, data from a United States study of remdesivir by Gilead showed the treatment cut patients' COVID-19 recovery time by five days compared with patients who got a placebo in a trial comprised of 1,062 subjects. "The interim analysis showed no benefits of remdesivir in any groups of COVID-19 (asymptomatic/mild/moderate/severe/critical) patients", ICMR said in a statement on October 16.
According to analysts, the results announced on Friday do not negate the previous ones, and the WHO study was not as rigorous as the earlier one led by the US National Institutes of Health.
Hydroxychloroquine's off-label use for moderately-ill coronavirus patients was approved by India's drug regulator, while remdesivir was approved for "emergency use authorization".
In comparison, the experts said, a key U.S. study that had influenced the regulatory decision to approve emergency authorisation use had involved 1,062 patients.
In the trial, 2,750 participants received remdesivir, 954 received hydroxychloroquine, 1,411 received Lopinavir, 651 received Interferon plus Lopinavir, 1,412 Interferon and 4,088 received placebo.
"When adding Solidarity to the trials we have to date, I think it is likely that a large mortality benefit does not exist, and in this context, the cost is too high", he said.
There is a bit of uncertainty in the data, but the study says it "absolutely excludes" the idea remdesivir can save a significant number of lives and says the findings are "comfortably compatible" with the drug having no life-saving effect at all.
After months of planning and testing a handful of repurposed drugs that studies from around the world have found useful in treating COVID-19, researchers in the largest scientific study for potential COVID-19 treatments has found many of them ineffective against the SARS-CoV-2 virus.
"The unpromising overall findings from the regimens tested suffice to refute early hopes, based on smaller or non-randomized studies, that any will substantially reduce inpatient mortality, initiation of ventilation or hospitalisation duration", the preliminary study found.
Under an agreement with the manufacturers, Gilead was entitled to see the results 10 days before the manuscript was submitted, Soumya Swaminathan, the WHO's chief scientist, said in the briefing.
"We're looking at what's next".
The WHO study has not yet been peer-reviewed, but it's available via a pre-print server.
"Covid affects millions of people and their families around the world", he added.
She called it a "good experience" all-in-all, and on Wednesday before the data was released, she said next plans will involve monoclonal antibodies, immunomodulators and new antiviral drugs developed within the last few months.