Health experts have slammed the US for buying virtually all stocks for the next three months of a drug shown to work against COVID-19.

The US Department of Health and Human Services said it had secured more than 500,000 treatment courses of remdesivir for American hospitals.

This represents 100 per cent of the US pharmaceutical firm Gilead’s projected production for July (94,200 treatment courses), 90 per cent of production in August (174,900 courses), and 90 per cent of production in September (232,800 courses), alongside an allocation for clinical trials.

Remdesivir is an anti-viral drug that was developed for use against ebola.

It has been approved for use in COVID-19 patients by the US and Britain, among other countries, after data suggested it could cut recovery time by about four days.

However, there is no clinical trial data as yet to suggest it improves survival from coronavirus.

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HHS secretary Alex Azar said in a statement: “President Trump has struck an amazing deal to ensure Americans have access to the first authorised therapeutic for COVID-19.

“To the extent possible, we want to ensure that any American patient who needs remdesivir can get it.”

Oxford University’s Professor Peter Horby, chairman of the New and Emerging Respiratory Virus Threats Advisory Group (Nervtag), said manufacturer Gilead would be under “certain political pressures locally” as a US company.

He told BBC Radio 4’s Today program: “It does raise two very important questions: What is a fair price for a drug, and what is fair access to a drug, and those are common issues but are particularly important in a global crisis like this.

“That’s part of the fair access question – the trial that gave the result that allowed remdesivir to sell their drug wasn’t just done in the US, there were patients participating through other European countries, in the UK as well, and internationally, Mexico and other places.

“I wonder how they would feel knowing now that the drug is going to have restricted availability in their own country and would they have volunteered for that trial if they had known that?”

It also raised questions if a vaccine was found, he said.

“Commercial companies are built to behave like this and we need a much stronger framework if we are going to develop these things and they’re going to be used for national emergencies.”

Gilead has said it will charge $US2340 ($A3400) for a typical treatment course for people in the US and other developed countries.

It will sell for less in poorer countries where generic drug-makers are being allowed to produce it.

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Critics in the US attacked the price because taxpayers have funded much of the drug’s development.

Gilead has said that cutting four days of hospital costs for each patient saves the US health system $12,000 per patient.

Based on that benchmark, it suggested it could have justified a higher price.

-with agencies