The US has secured nearly the entire world stock of antiviral drug remdesivir from US-based Gilead Sciences for the following three months, leaving hardly any stock of the important thing COVID-19 drug for the remainder of the world.

The US health department announced on Tuesday it had agreed to buy 500,000 doses for use in American hospitals.

Tests suggest remdesivir cuts recovery times, though it is not yet clear if it improves survival rates.

Gilead did sign a licensing deal in May for production outside the US but it is still in its early stages.

"President Trump has struck an amazing deal to ensure Americans have access to the first authorised therapeutic for Covid-19," Department of Health and Human Services Secretary Alex Azar said in a statement.

A course of treatment in the US will cost $2,340 (£1,900). Nine companies can make the drug under license outside the US for distribution in 127 mostly poorer countries, and the cost is lower. But the project is still in its early stages.

Additional quantities are being manufactured for use in clinical trials. But critics say the US move to buy up so much stock from Gilead itself undermines international co-operation on COVID, given that other countries have taken part in trials of remdesivir, originally an anti-viral against Ebola.

"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," Oxford University's Prof Peter Horby told BBC Radio 4.

He said the move also had implications for any possible future vaccine, with the need for "a much stronger framework if we are going to develop these things and they're going to be used for national emergencies".

Senior Sussex University lecturer, Ohid Yaqub, said: "It so clearly signals an unwillingness to co-operate with other countries and the chilling effect this has on international agreements about intellectual property rights."

Some in the US have criticized the purchase price, as taxpayer money had helped fund remdesivir's development.

Meanwhile back at home, the recovery rate of COVID-19 patients has improved to 59.43 percent. During the last 24 hours, 13,157 patients have been cured, taking the cumulative figure to 3,47,978. Presently, there are 2,20,114 active cases and all are under medical supervision.

As a result of the coordinated steps taken by the Central Government along with states for prevention, containment and management of COVID-19, there are 1,27,864 recovered cases more than the active COVID-19 cases, as on date.

In a statement, the Health Ministry said the testing lab network in the country is further strengthened. With 764 labs in the government sector and 292 private labs, there are as many as 1056 labs in the country.

There has been a steady rise in the number of samples tested each day. In the last 24 hours, 2,17,931 samples have been tested. The cumulative number of samples tested so far is over 88. 26 lakh.