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.

A new randomized study could cost Novavax tens of millions of dollars, vaccine experts say

Novavax says its closely watched COVID-19 vaccine is on track for full U.S. approval after additional discussions with the Food and Drug Administration