WASHINGTON, Dec. 19 (CNA-AFP) The United States on Friday (Dec 18) authorised Moderna's COVID-19 vaccine for emergency use, paving the way for six million doses of a second vaccine to soon begin shipping across the hardest-hit country in the world.

Food and Drug Administration (FDA) chief Stephen Hahn said: "With the availability of two vaccines now for the prevention of Covid-19, the FDA has taken another crucial step in the fight against this global pandemic."

"Congratulations, the Moderna vaccine is now available!" tweeted President Donald Trump.

The US is the first nation to authorise the two-dose regimen from Moderna, now the second vaccine to be deployed in a Western country after the first, developed by Pfizer and BioNTech.

The Pfizer-BioNTech vaccine was approved by Britain on December 2, followed by several other countries including the US last week. Less-vetted shots have also been rolled out in China and Russia.