Britain and Germany said they had sufficient stocks of remdesivir, the first drug to be shown to be relatively effective in treating COVID-19, and of which the United States has bought almost all supply.

Washington announced this week that it had purchased 92 percent of all remdesivir production by the Gilead laboratory until the end of September -- about 500,000 treatments out of nearly 550,000. Each treatment requires 6.25 vials on average.

President Donald Trump "has struck an amazing deal to ensure Americans have access to the first authorized therapeutic for COVID-19," said Secretary of Health and Human Services Alex Azar as the US death toll hit 127,000 -- the world's highest.

Gilead has set the price at $390 per vial in developed countries, or $2,340 for six vials used over the normal five-day course, though US private insurers will pay $520 per vial.

The drug was approved in the United States on May 1 after clinical trials showing it reduced the recovery time for seriously ill COVID-19 patients by four days, and Europe is set to approve it soon.

Washington's buy-up raised concerns about a shortage in the rest of the world, but at least two European countries said Wednesday that they were not worried.

"The UK has been using remdesivir for some time, first in trials and now in the early access to medicines scheme. The UK currently has a sufficient stock," the British Prime Minister's spokesman said.

In Germany, a health ministry spokesman said "the government secured stocks of remdesivir early on for the treatment of corona patients. At the moment, there are sufficient reserves."

- Generic supplies -

The Gilead laboratory has granted royalty-free licenses to nine manufacturers of generic drugs in India, Pakistan and Egypt.

They will have the right to distribute their versions of remdesivir in 127 developing countries, Gilead told AFP in a statement.

In other countries, "access to remdesivir will be prioritized first according to regulatory approvals and authorizations and the incidence of disease, and subsequently by severity of disease, to provide access to patients with the most urgent need," the company said.

Remdesivir will be produced by Gilead factories in the United States but also by manufacturing partners in North America, Europe and Asia, "to scale up supply," it added.

Experts say that worldwide production should increase to meet demand, but some expressed concern over companies "blocking" COVID-19 drugs.

"If you are worried that you or a loved one will need this drug and it won't be available if you are not in the US, I don't think that will be the case (and I certainly hope not)," Farasat Bokhari, associate professor in economics at the University of East Anglia, said.

"Manufacturers in other countries are going to ramp up production. The only issue is how fast they can do it."

He added that at least one manufacturer in Bangladesh -- Beximco -- produces remdesivir without a licence under a World Trade Organization intellectual property clause which allows developing countries to issue a "compulsory licence."

Matthew Kavanagh, health law expert at Georgetown University, told that AFP that "countries around the world should immediately announce a coordinated campaign of 'compulsory licences' on this and other COVID-19 medicines, so originator companies can get a royalty but they cannot block production of necessary drugs."