In yet another blow to slim hopes that hydroxychloroquine may have some value as a treatment for Covid-19, experts have found that taking the drug before coronavirus exposure does not reduce the risk of mortality.
Previous studies have shown that the 70-year-old malaria drug has no benefit when used as a treatment for patients suffering from Covid-19, or as a postexposure prophylaxis - that is, to prevent people developing an infection after coming into contact with the virus.
But the latest observational study, published in Lancet Rheumatology on Thursday, is the first of its kind to assess whether hydroxychloroquine reduces fatalities if given before an individual comes into contact with Covid.
The research used anonymised data from an analytics platform, called OpenSAFELY, to track some 30,000 patients who had been prescribed hydroxychloroquine to treat rheumatoid arthritis or lupus for at least six months before the pandemic first reached the UK.
Of this group, 70 died from Covid-19 between March and June. The researchers found there was no statistical difference between this mortality rate and that in a control group of people who had rheumatoid arthritis or lupus but did not take hydroxychloroquine.
“We found no association between hydroxychloroquine use and Covid mortality,” said Dr Christopher Rentsch, a pharmacoepidemiologist at the London School of Hygiene and Tropical Medicine and lead author of the report.
“But because this was based on observational data, I think we need to wait for the completion of the COPCOV trial for a definitive answer,” he added.
The COPCOV study , which is funded by organisations including the Bill & Melinda Gates Foundation and Wellcome, is a large-scale, randomised trial, which has enrolled thousands of healthcare workers to test whether hydroxychloroquine is effective as a preventive treatment.
The idea that the treatment may work against Covid-19 first emerged in the early days of the pandemic after a promising study in the lab.
Since then, the drug has gained notoriety as it has been touted by politicians including US president Donald Trump and his Brazilian counterpart, Jair Bolsonaro - who claimed that hydroxychloroquine helped him recover after he contracted Covid in March.
But while the latest research appears yet another nail in the coffin in terms of using the drug to treat Covid, Dr Rentsch stressed that while the drug saw no benefits, neither was it harmful. “Therefore the completion of randomised trials investigating pre-exposure are warranted,” he said.
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