Coronavirus: Hydroxychloroquine 'cure' touted by Trump 'harmful and should not be used'

The drug, which is cheap, is still widely used in parts of Asia and Brazil, which has the world's second highest death toll from the disease after the United States.

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And as late as last autumn, 95% of Covid hospital patients in Italy were being given the anti-malaria pills.

The recommendations follow an analysis of thousands of clinical trials worldwide carried out on behalf of the European Respiratory Society by a panel of experts from nine countries, led by Dundee University's Professor James Chalmers.

They found that that 44.3% of patients given hydroxychloroquine suffered side effects, compared to 15.4% on a control drug, equivalent to a 423% increased risk once additional calculations are made to account for the data coming from seven separate studies.

Prof Chalmers, a consultant respiratory physician and expert in chronic airway diseases, said: "It can potentially cause problems with the heart rhythm and in severe cases, if people are on other drugs that affect the heart, those side effects can be very serious."

The drug became hugely popular after being advocated by pandemic sceptics including Brazilian president Jair Bolsonaro and President Trump in the US, who continued to promote it last year after both the FDA and WHO dropped it as a potential treatment.

Mr Trump, who revealed he had taken the drug prophylactically, insisted it was safe and that he had "absolutely no problems", but was criticised for retweeting a video which claimed hydroxychloroquine was “a cure for Covid” and meant “you don’t need a mask” to slow the spread of the coronavirus.

The new recommendations will guide best practice worldwide for patients in hospital with Covid

Prof Chalmers said: "The hydroxychloroquine story really emphasises the danger of people recommending drugs when they don't really know what it is that they're recommending, and they don't have any evidence for it.

"It was massively promoted on the internet as well. Still not a day goes by that I don't get something on my Twitter account saying that I'm 'covering up' the wonderful effects of hydroxychloroquine.

"There are still people who massively believe in this."

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The new guidelines have the potential to save thousands of lives worldwide, however, after the scientists found that a combined therapy of tocilizumab - a rheumatoid arthritis drug - and the steroid dexamethasone can reduce complications by up to 40%.

Dexamethasone is already widely used in NHS hospitals in the UK and data has been emerging recently on the benefits of tocilizumab, but Prof Chalmers says clinicians "aren't sure which patients to use it in".

He added: "Worldwide there's a lot of variation in practice. Some countries aren't using it at all, and some places are using it only in the very sickest people in intensive care."

The ERS says the combined therapy should be given to all Covid patients who are receiving ventilation or oxygen treatment in hospital, whether in or outwith intensive care, which means it will apply to around eight in ten patients.

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In addition, the panel strongly recommends that blood thinning drugs should be given to anyone hospitalised with Covid due to the "shocking statistic" that one in three will develop clots.

However, Prof Chalmers said further research is needed to determine whether blood thinning drugs and anti-inflammatories should also be prescribed to some people to prevent them ending up in hospital.

He said: "There's a lot of people who stay home, really quite sick with Covid, who are at high risk of getting worse and are at risk of things like blood clots.

"So there really does need to be those studies in the community of where things like blood thinners or some of the anti-inflammatory medicines could prevent people in the community getting worse and ending up in hospital."

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The new guidelines also reject the use of remdesivir - an expensive anti-viral medication which was widely used across the UK last year, including in Scotland - on the basis that the evidence for any meaningful benefit to patients was weak.

There was no evidence that it was causing harm, however.

A major study by the World Health Organisation found remdesivir had no effect on mortality, but a smaller US trial did conclude that it cut the time spent in hospital.

"The panel were quite split on this," said Prof Chalmers.

"Some people felt - if it cuts the time you spend in hospital - it's probably still worth trying. But overall, we felt that it was quite expensive for little meaningful effect."

While vaccinations should limit the number of people hospitalised with Covid in the UK if cases surge again, most of the world is still reliant on medicines to cut deaths.

The new guidelines will be vital in shaping best practice for clinicians worldwide, and will be important in the UK where England's chief medical officer Professor Chris Witty said at least 30,000 more people could still die from the disease even with highly effective vaccines.

Prof Chalmers said: "I don't think we're out of the woods yet in the UK, and worldwide most other countries are way behind in terms of numbers vaccinated.

"I'm just off the phone with a colleague in Italy where they're experiencing a really severe third wave. Their intensive care units are full again.

"For those countries outside the UK that are still battling this at very high levels, it's important to know what works.

"A 30-40% reduction in mortality translates into tens or hundreds of thousands of lives saved over the next year or two."