The US Food and Drug Administration has discussed with vaccine-maker Novavax the need for an additional trial of its Covid-19 vaccine as a post-approval commitment, a source familiar with the matter told CNN.

At FDA, full vaccine approval is the gold standard. The agency was on track to sign off on Novavax’s license by its April 1 target date, according to two people with direct knowledge of the situation who spoke on condition of anonymity to discuss confidential agency matters.

Under emergency use, vaccines can be removed even after a health emergency is considered to be over. Full approval from the FDA means a product can stay on the market even after a health emergency ends. (The World Health Organization declared an end to the COVID emergency in May 2023.)