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Hydroxychloroquine fails trial as preventative measure against COVID-19

Drug performed no better than placebo when used in people exposed to infection

clinical trial

A study suggests that use of malaria drug hydroxychloroquine to ward of COVID-19 in people exposed to infection is futile, as the drug performed no better than placebo when used in this way.

The trial conducted in more than 800 patients in the US and Canada – which has just been published in the New England Journal of Medicine (NEJM) – recruited people who were at moderate to high risk of contracting COVID-19 because they had been in close contact with someone with the infection.

The subjects – mainly healthcare workers, first responders and people living with infected individuals – were given either hydroxychloroquine for five days as post-exposure prophylaxis (PEP) or placebo. After two weeks, 12% of people taking the drug had an infection, compared to 14% of the placebo group.

"The take-home message for the general public is that if you're exposed to someone with COVID-19, hydroxychloroquine is not an effective post-exposure, preventive therapy," said lead author David Boulware.

On the plus side, the trial found no evidence of serious complications with hydroxychloroquine, including the irregular heart rhythms reported in some patients that have raised red flags about its indiscriminate use for coronavirus.

The World Health Organization had halted the hydroxychloroquine arm of its multi-drug SOLIDARITY trial because of the safety concerns, but said this week it was resuming patient recruitment.

The study classed patients as high risk if they had been within 2m of a coronavirus patient for more than 10 minutes without personal protective equipment (PPE) such as a mask or face shield, and moderate risk if they used PPE. The split between the groups was 88% to 12%, respectively.

Boulware tweeted that the trial was however limited by a lack of swab testing for coronavirus in March and April, which meant the investigators had to rely on confirmed and probable cases with symptoms that matched COVID-19.


“It is hard to be certain how many participants in the trial actually had COVID-19,” says an editorial accompanying the study by Myron Cohen of the US-based Institute for Global Heath and Infectious Diseases.

The trial didn’t address whether taking the drug before exposure to coronavirus – a strategy famously deployed by President Donald Trump – would have any impact, or indeed if the drug would have an effect on asymptomatic infection.

Using zinc and vitamin C – also being touted in some quarters as possible home remedies to ward off the virus – also failed to have an impact on the study results. Boulware said trials of pre-exposure prophylaxis are ongoing.

He also noted that follow-up of a trial of early treatment with hydroxychloroquine in patients with COVID-19 infection had been completed, and that the data was currently being analysed.

An earlier study in the British medical Journal – conducted in China – found that hydroxychloroquine had no benefit in COVID-19 patients admitted to hospital with persistent mild to moderate symptoms.

Meanwhile, along with the SOLIDARITY study run by the WHO, there are other trials of the drug on the go including the University of Oxford’s multidrug RECOVERY study in 10,000 subjects which is also testing Gilead’s remdesivir, AbbVie's HIV drug Kaletra (lopinavir/ritonavir) and interferon beta-1a.

The largest study – called COPCOV – is aiming to recruit 40,000 around the world and is being led by the Mahidol Oxford Tropical Medicine Research Unit in Bangkok. That was also paused on safety concerns last month.

Article by
Phil Taylor

4th June 2020

From: Research



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