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

Federal regulators have asked Novavax to complete an additional clinical trial on its COVID-19 vaccine after previously delaying approval, the Wall Street Journal reported on Friday, citing people familiar with the matter.