Novavax shares jumped more than 15% on Monday after the company secured a long-awaited U.S. regulatory approval for its COVID-19 vaccine, albeit with new conditions, which helped allay some investor concerns over the future of the shot.

Previously granted Emergency Use Authorization, Nuvaxovid is now available for individuals over 12 years of age.

"The FDA will approve vaccines for high-risk persons and, at the same time, demand robust, gold-standard data on persons at low risk," the agency said in an article published by The New England Journal of Medicine, authored by FDA Commissioner Dr. Martin Makary and his new top vaccines official, Dr. Vinay Prasad.

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.

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

The US Food and Drug Administration has fully approved a new COVID vaccine option specifically targeting high-risk individuals, including seniors. The protein-based Nuvaxovid vaccine, produced by Novavax,

The agency will narrow its approval for updated coronavirus vaccines, marking a significant shift in the agency’s approach to green-lighting shots that have been recommended broadly to the public.

The Food and Drug Administration has issued a long-awaited approval of Novavax’s COVID-19 vaccine but with unusual restrictions.

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.