Novavax shares surged more than 17% before the bell on Monday, following the long-delayed approval of its COVID-19 vaccine from the U.S. health regulator, albeit with new conditions.

This vaccine did previously have emergency approval by the FDA for use but can now be marketed in the U.S. for use, the letter said.

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