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.

Panel members had questions about whether a new FDA proposal to require randomized trials for vaccines in healthy adults might delay manufacture and limit access.

The FDA has approved the Novavax COVID-19 vaccine, called Nuvaxovid, mainly for adults 65 or older, but people ages 12 to 64 with medical conditions that increase their risk of serious illness from COVID can also get the shot.