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.

Key Takeaways Novavax received Food and Drug Administration approval for its new, protein-based COVID-19 vaccine.The shot, Nuvaxovid, is designed for older adults and those between the ages of 12 and 64 who have underlying conditions that puts them at higher risk from the disease.

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.