A major British clinical trial has found Hydroxychloroquine has “no benefit” for patients hospitalised with COVID-19, scientists said Friday, in the first large-scale study to provide results for a drug at the centre of political and scientific controversy.

Hydroxychloroquine, decades-old malaria and rheumatoid arthritis drug, has been touted as a possible treatment for the new coronavirus by high profile figures, including US President Donald Trump, and has been included in several randomised clinical trials.

The University of Oxford’s Recovery trial, the biggest of these so far to come forward with findings, said that it would now stop recruiting patients to be given Hydroxychloroquine “with immediate effect”, an AFP report said.

“Our conclusion is that this treatment does not reduce the risk of dying from COVID among hospital patients and that clearly has significant importance for the way patients are treated, not only in the UK, but all around the world,” said Martin Landray, an Oxford professor of medicine and epidemiology who co-leads the study.

The randomised clinical trial — considered the gold standard for clinical investigation — has recruited a total of 11,000 patients from 175 hospitals in the UK to test a range of potential treatments.

Researchers said 1,542 patients were randomly assigned to Hydroxychloroquine and compared with 3,132 patients given standard hospital care alone.

They found “no significant difference” in mortality after 28 days between the two groups, and no evidence that treatment with the drug shortens the amount of time spent in hospital.

“This is a really important result, at last providing unequivocal evidence that Hydroxychloroquine is of no value in treatment of patients hospitalised with COVID-19,” said Peter Openshaw, a professor at Imperial College London, in reaction to the results.

He added that the drug was “quite toxic” so halting the trials would be of benefit to patients.

The observation comes two days after the World Health Organization announced on Wednesday that clinical trials of Hydroxychloroquine drug will resume as it searches for potential coronavirus treatments.

On May 25, the WHO announced it had temporarily suspended the trials to conduct a safety review, which has now concluded there is “no reason” to change the way the trials are conducted.

At a press conference in the WHO headquarters in Geneva, Director General Tedros Adhanom Ghebreyesus said: “On the basis of the available mortality data, the members of the committee recommended that there are no reasons to modify the trial protocol.

“The Executive Group received this recommendation and endorsed continuation of all arms of the solidarity trial, including Hydroxychloroquine.”

The UN health agency’s decision to suspend the trials came after a study published in The Lancet medical journal suggesting the drug could increase the risk of death among COVID-19 patients.

The decision to resume came as The Lancet issued a correction after more than 100 scientists and medical professionals raised questions about integrity of data analysed in the study. In the correction issued on Friday, Lancet said that one hospital self-designated as belonging to the Australasia continental designation should have been assigned to the Asian continental designation.

Meanwhile, a separate clinical trial on Wednesday in the US and Canada found that taking hydroxychloroquine shortly after being exposed to COVID-19 does not work to prevent infection significantly better than a placebo.

(With AFP inputs)