Remdesivir, developed for Ebola by US pharmaceutical company Gilead Sciences, was one of the earliest treatments put forward for COVID-19 and was taken by US President Donald Trump when he was admitted to hospital with the disease at the beginning of the month.
The data from the ACTT-1 trial on 1,062 patients by the U.S. government's National Institute of Allergy and Infectious Diseases (NIAID) published in the New England Journal of Medicine (NEJM) has found that hospitalized patients with COVID-19 pneumonia who received Remdesivir recovered five days faster than patients receiving placebo at day 29, and had evidence of lower respiratory tract infection.
SOLIDARITY's findings are particularly grim news for the USA, where remdesivir is one of just two treatments to have gotten emergency Food and Drug Administration (FDA) authorization.
The WHO's Solidarity trial, one of the largest ongoing studies of Covid-19 drugs, examined the effects of remdesivir and three other potential coronavirus treatments in more than 11,000 patients in 30 countries.
Gilead, which makes the drug, told the Financial Times that the data "appear inconsistent with more robust evidence from multiple randomized, controlled studies validating the clinical benefit of [remdesivir]". Drugs can be added or removed from the trial at any time.
It didn't look into other uses of the drugs for COVID-19, like in treating patients in a COVID-19-infected community, or for COVID-19 prevention.
"We are concerned that the data from this open label global trial have not undergone the rigorous review required to allow for constructive scientific discussion, particularly given the limitations of the trial design", Gilead added. He said the drug is now recommended in some countries but there have been significant concerns about supply, cost and access. Almost 39 million people around the world have been diagnosed with COVID-19 and more than one million have died.
The trial was able to generate conclusive evidence on the impact the drugs had on mortality, the need for ventilation, and duration of hospital stay.
Remdesivir has been the frontrunner in re-purposed drugs with various studies showing a positive recovery rate in patients.
The attention is now turning to new experimental therapies such as antibodies designed in the lab to fight the virus and new, untested, anti-viral drugs.
"We're looking at what's next".
WHO's Solidarity trial will continue to evaluate other treatments, including newer antiviral drugs, immunomodulators, and anti-SARS COV-2 monoclonal antibodies, the United Nations agency said.
However the researchers said it was not possible to say whether the antibody responses induced by the vaccine were sufficient to protect from infection because the trial was not created to assess its efficacy.