Moderna has been approved by the US government as the country’s second Covid-19 vaccine, clearing the way for millions of doses to be released.
The Food and Drug Administration (FDA) authorised the US-made jab about a week after approving a Pfizer/BioNTech vaccine which is now being distributed.
The US has agreed to purchase 200 million doses of Moderna, and six million may be ready to ship now.
The country has the world’s highest numbers of Covid-19 deaths and cases.
It has recorded more than 313,500 deaths and about 17.5 million infections, according to Johns Hopkins University.
FDA commissioner Stephen Hahn said the emergency approval of the vaccine on Friday marked “another crucial step in the fight against this global pandemic that is causing vast numbers of hospitalizations and deaths in the United States each day”.