After a six-week delay, the US Food and Drug Administration has approved Novavax’s Covid-19 vaccine, according to a letter from the agency, but only for people 65 and older and those 12 and up who have at least one underlying condition that puts them at higher risk of severe illness.

The notice came shortly after an advisory panel meeting at which members debated the pros and cons of asking manufacturers to update their vaccines.

The U.S. Food and Drug Administration approved Novavax's COVID-19 vaccine with age restrictions after a six-week delay.