The US President has lashed out at researchers behind studies suggesting his favoured coronavirus remedy hydroxychloroquine doesn't work, calling them an "enemy".
Donald Trump this week claimed he's been taking the anti-malarial drug to ward off COVID-19 despite there being no evidence it can prevent the deadly disease, which has killed more than 334,000 people worldwide - including 96,000 US citizens.
His support for the drug dates back to March, when the pandemic really started to take hold in the US. A small French study published that month claimed hydroxychloroquine could significantly reduce the viral load in COVID-19 patients, and even wipe it out completely. The study has been widely criticised in subsequent weeks, with concerns about its design and the way it was reported. The organisation which published the research even backtracked, saying it was below standard.
Trump said it had a "real chance to be one of the biggest game changers in the history of medicine".
Since then, a number of studies have found hydroxychloroquine doesn't seem to help COVID-19 patients, and may even cause adverse outcomes.
One study, which looked at the outcomes of COVID-19 patients at hospitals run by the US Veterans Health Administration, found patients were more than twice as likely to die when treated with hydroxychloroquine.
Trump, speaking to reporters earlier this week, said the study was conducted by "people that aren't big Trump fans".
"If you look at the one survey, the only bad survey, they were giving it to people that were in very bad shape. They were very old, almost dead. It was a 'Trump enemy' statement."
He went on to say the drug "doesn't hurt people".
"It's been out on the market for 60 or 65 years for malaria, lupus, and other things. I think it gives you an additional level of safety."
The Veterans Health Administration study was retrospective, not a randomised controlled trial, and it's not known how the doctors who treated the patients involved decided who should receive hydroxychloroquine and who shouldn't.
After the results were released in late April, the US Food and Drug Administration issued a warning against using hydroxychloroquine "outside of the hospital setting or a clinical trial". Trump is neither in hospital nor part of a clinical trial.
Even with its potential flaws, Trump was incorrect to say the Veterans Health Administration study was the "only bad" one. A meta-analysis conducted by researchers from the Majumdar Shaw Medical Centre in Bangalore and uploaded on Thursday looked at 11 different studies on hydroxychloroquine's effectiveness against COVID-19, covering more than 4000 patients, and concluded there was no evidence it worked at all.
"The overall mortality was not significantly different among patients who received hydroxychloroquine compared to the control group," they wrote. "Clinical worsening or lack of symptomatic improvement did not differ between patients who received hydroxychloroquine compared to those who did not. Viral clearance... did not differ significantly between the hydroxychloroquine and the control groups."
Also, there was "a significantly higher incidence of adverse events with hydroxychloroquine use".
Some have suggested Trump keeps pushing the drug because he, his family and donors to his political campaigns have financial interests in Sanofi, the company that makes the best-known brand name version, Plaquenil.
Demand for the drug in April saw it in short supply, leaving those who need it for conditions it works against - like malaria, rheumatoid arthritis and lupus, potentially going without.
A number of trials of the drug, which is on the World Health Organization's Model List of Essential Medicines, and its effectiveness on COVID-19 are ongoing.
