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.

Novavax Inc. jumped after US regulators fully approved its Covid vaccine, easing investors’ concerns after the clearance was delayed and US Health and Human Services Secretary Robert F. Kennedy Jr. raised doubts about its efficacy.

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.