The US drug regulator gave Moderna Inc clearance to speed up the output of its Covid-19 vaccine by letting it fill a single vial with up to 15 doses, with the United States banking on rapid immunisation to stem the spread of the deadly virus.

The US Food and Drug Administration (FDA) also authorised vaccinators to extract a maximum of 11 doses from the current vials, instead of the ten previously permitted.

In a statement, Moderna said its vaccine can now be supplied in vials...