WASHINGTON - Moderna on Tuesday (June 1) filed for full United States approval of its Covid-19 vaccine, which is currently authorised only for emergency use in the country, becoming the second drugmaker to seek a broader regulatory nod.

The development comes weeks after rival Pfizer and its German partner BioNTech sought full approval for their Covid-19 vaccine in the US.

Full approval for the vaccines, which are at the forefront of global immunisation efforts, could be an important step in allaying vaccine hesitancy, a growing concern in the US and other wealthy nations.

It would also allow the vaccine makers to market their shots directly, as well as help companies and government agencies looking for vaccinations for their employees.

Moderna said it will continue to submit data to the US Food and Drug Administration (FDA) on a rolling basis over the coming weeks with a request for a priority review.

On completion of the submission, the FDA will notify the company when it is formally accepted for review, it added.

Moderna has an agreement with the US government to supply 300 million doses of its Covid-19 vaccine.

More than 151 million doses of Moderna's vaccine have been distributed around the US, with roughly 124.5 million shots administered as at Monday, according to the US Centres for Disease Control and Prevention.

Under an emergency-use authorisation, the FDA makes a product available to the public during an emergency based on the best available evidence, without waiting for all the evidence needed for full approval or clearance.

Moderna said in April its vaccine showed strong protection against the coronavirus six months after people received their second shot, with efficacy of more than 90 per cent against all cases of Covid-19 and more than 95 per cent against severe Covid-19.