Chennai: The US green lighted the Pfizer-BioNTech Covid-19 vaccine, paving the way for millions of vulnerable people to receive their shots in the world’s hardest-hit country.

President Trump immediately released a video on Twitter, where he hailed the news as a ‘medical miracle’ and said the first immunisations would take place ‘in less than 24 hours’.

It comes as infections across America soar as never before, with the grim milestone of 300,000 confirmed deaths fast approaching.

The US is now the sixth country to approve the two-dose regimen, after Britain, Bahrain, Canada, Saudi Arabia and Mexico.

The move came earlier than expected, and capped a day of drama after it was widely reported that the White House had threatened to fire Food and Drug Administration chief Stephen Hahn if he did not grant emergency approval Friday.

Trump’s intervention reinserts politics into the scientific process, which some experts have said could undermine vaccine confidence.

The US is seeking to inoculate 20 million people this month alone, with long-term care facility residents and health care workers at the front of the line.

The government also said Friday that it is buying 100 million more doses of the Moderna vaccine candidate, amid reports the government passed on the opportunity to secure more supply of the Pfizer jab.