The U.S. Food and Drug Administration (FDA) refused to consider Moderna’s application for a new flu vaccine using mRNA technology, the company announced Tuesday, a decision that could delay the introduction of a shot designed to offer stronger protection for older adults. Moderna said it received what’s known as a ‘refusal-to-file’ (RTF) letter from the FDA’s Center for Biologics Evaluation and Research (CBER), citing the lack of an ‘adequate and well-controlled’ study with a comparator...










