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RTF flu vaccine letter heard around the world

syringe with a needle is seen in front of the moderna logo
Photo: Alex Gottschalk/DeFodi Images via Getty Images

The FDA issued an extremely rare refuse-to-file letter related to Moderna’s new mRNA flu vaccine.

Existential questions about the future of vaccine development have been raised by the refusal of the US Food and Drug Administration (FDA) to approve Moderna’s new flu shot.

On February 3, the Cambridge, Mass.-based pharmaceutical giant received a so-called “refusal-to-file” letter (RTF) from the FDA’s Center for Biologics Evaluation and

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