What are the key takeaways from this The Readout Loud episode?

Key insights include: **Regulatory Precedent Reversal:** Moderna received written FDA approval in 2023 for using standard-dose flu vaccine as comparator in their phase three trial, matching the exact methodology used by two currently approved enhanced flu vaccines (Fluzone HD and Flublok) that showed 24% and 30% efficacy improvements respectively, yet Prasad now rejects this approach eighteen months after trial initiation.; **mRNA Manufacturing Advantage:** mRNA flu vaccines allow strain selection as late as June versus February for traditional egg-based vaccines, enabling better matching to circulating viruses. The US has selected different COVID strains than Europe in two of the last four years using this flexibility, demonstrating potential for improved flu vaccine effectiveness through later strain selection and regional customization.; **Refuse-to-File Rarity:** FDA refuses to file only four percent of applications, typically due to missing data or quality defects that make applications nonreviewable. This case marks an unprecedented situation where the agency rejects an application based on trial design it previously approved in writing, with the center director overriding vaccine office staff recommendations to proceed with standard review.

What did Matt Herper and Steven Hogue discuss on The Readout Loud?

The FDA refuses to review Moderna's mRNA flu vaccine application despite prior approval of trial design. Director Vinay Prasad overrules vaccine office staff, demanding high-dose comparator instead of standard-dose vaccine used in the 41,000-person trial that showed 27% greater effectiveness and 49% fewer hospitalizations. Key topics include: **Regulatory Precedent Reversal:** Moderna received written FDA approval in 2023 for using standard-dose flu vaccine as comparator in their phase three trial, matching the exact methodology used by two currently approved enhanced flu vaccines (Fluzone HD and Flublok) that showed 24% and 30% efficacy improvements respectively, yet Prasad now rejects this approach eighteen months after trial initiation.; **mRNA Manufacturing Advantage:** mRNA flu vaccines allow strain selection as late as June versus February for traditional egg-based vaccines, enabling better matching to circulating viruses. The US has selected different COVID strains than Europe in two of the last four years using this flexibility, demonstrating potential for improved flu vaccine effectiveness through later strain selection and regional customization..

How long is this episode of The Readout Loud?

This episode is 50 minutes long. SignalCast provides an AI-generated summary so you can get the key insights in about 3 minutes.

The Readout Loud

388: The FDA's refusal to review Moderna's mRNA flu vaccine

February 12, 2026

50 min episode · 2 min read

Matt Herper,Steven Hogue

Episode

50 min

Read time

2 min

Topics

Investing, Fundraising & VC, Design & UX

AI-Generated Summary

Published Feb 13, 2026

Key Takeaways

✓Regulatory Precedent Reversal: Moderna received written FDA approval in 2023 for using standard-dose flu vaccine as comparator in their phase three trial, matching the exact methodology used by two currently approved enhanced flu vaccines (Fluzone HD and Flublok) that showed 24% and 30% efficacy improvements respectively, yet Prasad now rejects this approach eighteen months after trial initiation.
✓mRNA Manufacturing Advantage: mRNA flu vaccines allow strain selection as late as June versus February for traditional egg-based vaccines, enabling better matching to circulating viruses. The US has selected different COVID strains than Europe in two of the last four years using this flexibility, demonstrating potential for improved flu vaccine effectiveness through later strain selection and regional customization.
✓Refuse-to-File Rarity: FDA refuses to file only four percent of applications, typically due to missing data or quality defects that make applications nonreviewable. This case marks an unprecedented situation where the agency rejects an application based on trial design it previously approved in writing, with the center director overriding vaccine office staff recommendations to proceed with standard review.
✓Supporting Immunogenicity Data: Moderna conducted a separate phase three study comparing their mRNA vaccine to Fluzone HD in patients 65 and older, showing statistically superior neutralizing antibody titers and seroconversion rates. The FDA specifically requested this data be included in the August 2025 submission, yet still refused to review the complete package containing both efficacy and immunogenicity evidence.
✓Industry Investment Impact: Developing vaccines requires approximately one billion dollars and five years of FDA collaboration for phase three trials. Changing regulatory requirements after trial completion creates unpredictable investment environment where companies cannot rely on written agency guidance, potentially deterring future vaccine innovation beyond just mRNA technology across all therapeutic areas requiring large-scale clinical trials.

What It Covers

The FDA refuses to review Moderna's mRNA flu vaccine application despite prior approval of trial design. Director Vinay Prasad overrules vaccine office staff, demanding high-dose comparator instead of standard-dose vaccine used in the 41,000-person trial that showed 27% greater effectiveness and 49% fewer hospitalizations.

Key Questions Answered

•Regulatory Precedent Reversal: Moderna received written FDA approval in 2023 for using standard-dose flu vaccine as comparator in their phase three trial, matching the exact methodology used by two currently approved enhanced flu vaccines (Fluzone HD and Flublok) that showed 24% and 30% efficacy improvements respectively, yet Prasad now rejects this approach eighteen months after trial initiation.
•mRNA Manufacturing Advantage: mRNA flu vaccines allow strain selection as late as June versus February for traditional egg-based vaccines, enabling better matching to circulating viruses. The US has selected different COVID strains than Europe in two of the last four years using this flexibility, demonstrating potential for improved flu vaccine effectiveness through later strain selection and regional customization.
•Refuse-to-File Rarity: FDA refuses to file only four percent of applications, typically due to missing data or quality defects that make applications nonreviewable. This case marks an unprecedented situation where the agency rejects an application based on trial design it previously approved in writing, with the center director overriding vaccine office staff recommendations to proceed with standard review.
•Supporting Immunogenicity Data: Moderna conducted a separate phase three study comparing their mRNA vaccine to Fluzone HD in patients 65 and older, showing statistically superior neutralizing antibody titers and seroconversion rates. The FDA specifically requested this data be included in the August 2025 submission, yet still refused to review the complete package containing both efficacy and immunogenicity evidence.
•Industry Investment Impact: Developing vaccines requires approximately one billion dollars and five years of FDA collaboration for phase three trials. Changing regulatory requirements after trial completion creates unpredictable investment environment where companies cannot rely on written agency guidance, potentially deterring future vaccine innovation beyond just mRNA technology across all therapeutic areas requiring large-scale clinical trials.

Notable Moment

Former FDA biologics center head Jesse Goodman states he cannot recall ever overriding a review office decision during his 2003-2009 tenure. He emphasizes that disagreements over trial design typically get resolved during the review process through advisory committees and scientific dialogue, not through refuse-to-file letters that bypass standard evaluation procedures entirely.

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Episode Transcript

New setback for drugmaker Moderna and its push to develop an mRNA flu vaccine. Food and Drug Administration notified the pharmaceutical company Moderna on Tuesday that it would not be reviewing Moderna's new mRNA flu vaccine. This is the normal, back and forth dialogue that the FDA has with companies, especially when they don't follow the guidance. FDA commissioner doctor Martin McCarrie, thank you very much indeed for joining us this morning. Do. Welcome to this week's episode of The Read Out Loud, a weekly biotech podcast from STAT. I'm Allison DeAngelis. I'm Adam Feuerstein. And I'm Elaine Chen. It is Thursday, February 12, and we are going to diverge from our normal podcasting format this week and devote the entire episode to one controversial and impactful topic, the FDA's decision to block the review of Moderna's new flu shot. Stout was the first to report that Vinay Prasad, the agency's top regulator of vaccines, overruled the head of the FDA's vaccine office and other staffers in making that decision. Prasad's unilateral action against Moderna has renewed concerns about the FDA's regulatory posture under the Trump administration. To help us dig deeply into this important story and its ramifications, we'll be joined by stat reporters Lizzie Lawrence and Matt Herper. You will also hear directly from Moderna president Steven Hogue and former FDA official Jesse Goodman. But first, a word from our sponsor. So we're gonna chat with Moderna Stephen Hogue. But first, let's bring on, stat reporter Matt Harper. Matt, welcome back to the podcast. Thanks for having me, guys. Matt, can you give us a quick summary of what happened this week? So one of the big ideas for mRNA vaccines has always been to develop flu shots using that technology. You can pick flu strains faster. It should be a good thing. Moderna ran a global randomized clinical trial with 41,000 volunteers that compared their experimental mRNA flu shot to a standard dose flu vaccine in people aged 50 and older. Moderna's vaccine was twenty seven percent more effective in preventing influenza like illness and forty nine percent more effective against hospitalizations. But the FDA, or in this case, specifically, Vinay Prasad, told Moderna that its clinical trial was not adequate and well controlled, and therefore, its application would not be reviewed. Prasad objected to Moderna's use of a standard flu vaccine as the comparator in its clinical trial. Instead, Moderna, he said, should have used a high dose flu vaccine, which is more effective in people 65. Moderna acknowledged that the FDA had advised the company it would prefer a high dose vaccine in its control arm of the study, but also that the FDA assured the company that using the standard vaccine would be, in quotes, acceptable. Prasad's decision to block the review of Moderna's application is highly unusual. It only occurs in about four percent of cases. Normally, this dispute over the proper control arm in a clinical trial would be an issue brought …

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