Remdesivir, which has previously been initially developed as a failed Ebola treatment but has now been found to speeds up recovery times among Covid-19 patients, is exclusively manufactured by American pharmaceutical giant Gilead Sciences.

The US Department of Health and Human Services (HSS) has announced it has bought up more than 500,000 doses of the drug.

This makes up the entire global supply for July and 90 per cent of stocks for August and September.   

The US’s decision to stockpile the drug means there will likely be little supply in the rest of the world for several months.

Remdesivir, produced by California-based pharmaceutical giant Gilead Sciences,  was initially developed to treat Ebola but has proven to be effective against coronavirus.

It costs around £2,580 ($3,200) for a six dose course of the drug, according to the US government.

Remdesivir is the ‘biggest step forward’ in treating Covid-19 since the outbreak spiralled out of control. 

HSS secretary Alex Azar, hailed the move, saying president Donald Trump had struck an “amazing deal”.

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

“The Trump Administration is doing everything in our power to learn more about life-saving therapeutics for Covid-19 and secure access to these options for the American people.”

Gilead has been criticised in recent days for its decision to charge $2,340 (£1,990) for a typical remdesivir treatment course for people covered by government health programmes in the US and other developed countries.

In 127 poor or middle-income countries, the company is allowing generic makers to supply the drug; two countries are doing that for around $600 per treatment course.

Despite its ability to shorten the recovery times of some coronavirus patients, remdesivir has not been found to significantly improve an individual’s chances of surviving the disease.

“We’re in uncharted territory with pricing a new medicine, a novel medicine, in a pandemic,” Gilead’s chief executive, Dan O’Day, said.

He added the company believed it had to “really deviate from the normal circumstances” and price the drug to ensure wide access rather than based solely on value to patients.

Remdesivir is under patent to Gilead, which means no other developed countries are able to make it.  

The evidence around remdesivir is mixed but scientific studies have shown it helps the most severely ill people who need ventilation.

Gilead’s chief executive Daniel O’Day revealed a pricing structure for the drug in an open letter this week. 

Mr O’Day wrote the firm had set the price for developed countries ‘to ensure broad and equitable access at a time of urgent global need’.

It did not announce which countries this would apply to — and said the $390 price would apply to Americans covered by government healthcare.  

For US private insurance companies, the cost will be $520 (£420) per vial, or a total of $3,120 (£2,540) per patient. 

The US government has come under fire for its tactics in the global marketplace for coronavirus treatments.

It has shown a willingness to outbid other countries and keep supplies for itself rather than cooperating with them.

French pharmaceutical manufacturer Sanofi announced in May that the US would get its coronavirus vaccine first if it works but later changed its mind under pressure from the French government.

Justin Trudeau, the Canadian Prime Minister, has warned: ‘We know it is in both of our interests to work collaboratively and cooperatively to keep our citizens safe.’

Another option for the British government would be to use a ‘compulsory license’ which is a legal tool that would allow the Gilead’s patents for the drug to be ignored.

Generic versions of the drug could them be bought from countries such as India which do not recognise the patent.

The only other medicine which has so-far proven to be effective against Covid-19 is anti-inflammatory steroid dexamethasone.

Dexamethasone, a £5 steroid that has existed for decades, was the first drug proven to reduce the death rate among hospitalised patients needing oxygen.