There’s new uncertainty about updated COVID-19 shots this fall after the Trump administration’s handling of a shot from Novavax.

Novavax faces uncertainty as FDA requests a new clinical trial for its COVID-19 vaccine, the last protein-based option in the U.S., amid administrative changes. This move complicates efforts to update vaccines for new strains and raises concerns regarding similar requirements for mRNA vaccines by Pfizer and Moderna.

Comments over the weekend by FDA chief Martin Makary suggest the agency views Novavax’s updated COVID shot as a “new product” requiring additional clinical study.