Novavax had expected full approval for broader use by April 1, after the FDA reviewed data from a 30,000-person clinical trial showing the vaccine was safe and effective. But instead of a broad approval, the FDA asked the company to conduct more research.

President Donald Trump’s administration is slated to lay out its approach to Covid vaccination at an event Tuesday that could spell major changes in what is required to get regulatory approval for immunizations.

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.