US FDA approves second Covid booster for Americans 50 and older

• Immunocompromised people also eligible for second booster
• CDC now to decide how and when such doses are offered

The US Food and Drug Administration (FDA) has authorised second Covid-19 booster doses of Pfizer or Moderna vaccines for older and immunocompromised Americans.

The coronavirus pandemic has killed more than 977,000 people in the US but case numbers have been falling. Authorities have nonetheless warned that the US could experience a surge fuelled by virus subvariants or a new variant.