FDA's Botched Review of Moderna's Flu mRNA Vaccine

When the FDA licensed Moderna's new mRNA flu vaccine last week, legacy media coverage focused almost exclusively on efficacy. The pivotal trial reported that the vaccine was '26.6% more effective' than a conventional flu vaccine at preventing protocol-defined influenza-like illness. What received far less scrutiny was a much more serious problem in the trial data published in The New England Journal of Medicine —much of it relegated to an appendix behind a paywall. An analysis of that appendix alongside the FDA's own briefing document exposes clear regulatory malfeasance. A statistically significant safety signal from the pivotal trial was systematically diluted until it disappeared from the official story. Moderna's pivotal Phase 3 trial (P304) enrolled roughly 40,000 adults aged 50 and older, randomised 1:1 to either the company's mRNA-1010 vaccine or a traditional trivalent flu vaccine. This study evaluated an 'optimised' version of Moderna's vaccine after earlier versions produced disappointing efficacy results. Even with this updated formulation, the headline '26.6% relative efficacy' figure was misleading. In absolute terms, the vaccine reduced the risk of illness by just 0.8%. Most concerning, however, were the serious adverse event (SAE) data. The six-month data show that 449 participants in the mRNA group experienced at least one SAE, compared with 389 in the conventional group— an excess of 60 people . So, while the pivotal trial showed there were 4 fewer influenza hospitalisations in the mRNA group, 60 additional people experienced an SAE. SAEs are not mild events—they are usually severe enough to require hospitalisation, threaten life, cause significant disability, or result in death. The imbalance of SAEs in Moderna's pivotal trial was statistically significant —meaning it was unlikely to be a random fluke. Keep reading