While the drug has been ruled out as a method to treat infections, it may still be able to prevent them.
The Oxford researchers are leading a global study into whether hydroxychloroquine can prevent Covid-19, and have warned the drug is being discarded prematurely and could still save lives.
Known as Copcov, it's a double-blind, randomised, placebo-controlled study aiming to enrol 40,000 healthcare workers to determine if the malaria drug can prevent Covid-19.
Hydroxychloroquine has been routinely dismissed as an acceptable coronavirus treatment, with multiple scientific studies, including ones commissioned by the US National Institutes of Health (NIH) and the World Health Organisation (WHO), suggesting it can actually do more harm than good.
Proffesor Amanda Adler told JACKfm the John Radcliffe Hospital is among the sites which is participating in the the study.
However the Oxford University researchers have now stressed that, while the drug has been ruled out as a method to treat infections, it may still be able to prevent them.
The trial’s co-principal investigator Dr Will Schilling said: “We really don’t know if hydroxychloroquine works or not in prevention or very early treatment. That question remains unanswered.
“The benefits found in small post-exposure treatment trials, although modest, could be very valuable if they were confirmed.”
Professor Nick Day, director of the Mahidol Oxford Tropical Medicine Research Unit which is also guiding the study, said the Copcov trial will be able to find a definitive answer to the drug’s effectiveness.
He said: “By the time patients are admitted to hospital virus multiplication is well past its peak and inflammation in the lungs and other complications may prove lethal.
“At this stage the steroid dexamethasone, which reduces inflammation, saves lives but the antivirals hydroxychloroquine and chloroquine do not.
“However, that does not rule out that they could be effective much earlier in the illness. Prevention is much easier than cure. The Copcov study will find out if these drugs can prevent Covid-19 or not.”
The Oxford-led study was recently paused following controversy over a study from The Lancet, which claimed the drug caused higher death rates and heart problems.
The WHO halted its research due to these fundings but resumed it after errors were found in the Lancet study.
The effectiveness of hydroxychloroquine has frequently been championed by US President Donald Trump, while the nation’s top infectious disease expert Dr Anthony Fauci has backed the conclusions of the NIH and WHO in dismissing the drug.