Scientists in UK have halted a major drug trial after they found that the anti-malarial drug hydroxychloroquine, touted by US President Donald Trump as a potential "game changer" in the pandemic, was "useless" at treating COVID-19 patients.The coronavirus pandemic has infected more than 6.4 million people and killed nearly 400,000 worldwide.

"This is not a treatment for COVID-19. It doesn't work," Martin Landray, an Oxford University professor who is co-leading the RECOVERY trial, said.

"This result should change medical practice worldwide. We can now stop using a drug that is useless." Peter Horby, an Oxford University professor who is co-leading the RECOVERY trial with Landray, said his team had informed the WHO of their decision to halt the UK study.

Vocal support from Trump raised expectations for the decades-old drug that experts said could have been a cheap and widely available tool, if proven to work, in fighting the pandemic.

Controversy surrounding the drug grew after a study published in medical journal The Lancet last month raised safety concerns and led several COVID-19 studies of it to be halted. The Lancet study was then retracted on Thursday after its authors said they were unsure about its data. The RECOVERY trial of hydroxychloroquine had randomly assigned 1,542 COVID-19 patients to hydroxychloroquine and compared them with 3,132 COVID-19 patients randomly assigned to standard care without the drug.

Results showed no significant difference in death rates after 28 days, in length of stay in hospital or in other outcomes, the researchers said. The World Health Organisation (WHO) said on Wednesday it would resume tests of hydroxychloroquine as part of its 'Solidarity' trials, after those running the study briefly stopped giving it to new patients in light of the Lancet paper.

Scientists in UK have halted a major drug trial after they found that the anti-malarial drug hydroxychloroquine, touted by US President Donald Trump as a potential "game changer" in the pandemic, was "useless" at treating COVID-19 patients.The coronavirus pandemic has infected more than 6.4 million people and killed nearly 400,000 worldwide.

"This is not a treatment for COVID-19. It doesn't work," Martin Landray, an Oxford University professor who is co-leading the RECOVERY trial, said.

"This result should change medical practice worldwide. We can now stop using a drug that is useless." Peter Horby, an Oxford University professor who is co-leading the RECOVERY trial with Landray, said his team had informed the WHO of their decision to halt the UK study.

Vocal support from Trump raised expectations for the decades-old drug that experts said could have been a cheap and widely available tool, if proven to work, in fighting the pandemic.

Controversy surrounding the drug grew after a study published in medical journal The Lancet last month raised safety concerns and led several COVID-19 studies of it to be halted. The Lancet study was then retracted on Thursday after its authors said they were unsure about its data. The RECOVERY trial of hydroxychloroquine had randomly assigned 1,542 COVID-19 patients to hydroxychloroquine and compared them with 3,132 COVID-19 patients randomly assigned to standard care without the drug.

Results showed no significant difference in death rates after 28 days, in length of stay in hospital or in other outcomes, the researchers said. The World Health Organisation (WHO) said on Wednesday it would resume tests of hydroxychloroquine as part of its 'Solidarity' trials, after those running the study briefly stopped giving it to new patients in light of the Lancet paper.