by tim » Tue Aug 25, 2026 8:17 am
A Standard Announced, and an Exemption That Does Not Fit
On May 1, 2025, the Department of Health and Human Services told the Washington Post that, under Secretary Kennedy, all new vaccines would undergo placebo-controlled safety testing before licensure. HHS called it a “radical departure” from previous practice (HHS 2025).
A placebo-controlled trial compares the vaccine with an inert injection, usually saline. An active-controlled trial compares it with another vaccine. The distinction determines what can be measured. Against saline, the adverse-event rate attributable to the vaccine can emerge against a relatively clean baseline. Against another vaccine, the trial measures only the difference between two products. If both produce the same adverse event at elevated rates, the comparison can obscure it.
HHS never issued the policy as a regulation or formal guidance. It announced it to reporters and immediately carved out an exemption. The department declined to specify exactly which vaccines the new requirement covered, but told the Post that influenza vaccines were excluded because they had been “tried and tested for more than 80 years.”
That exemption does not fit mFLUSIVA.
The 80-year safety record belongs to conventional influenza vaccines. mFLUSIVA is the first licensed influenza vaccine built on an mRNA-lipid nanoparticle platform. The influenza antigen is familiar; the technology used to deliver the genetic instructions for producing it is not. HHS defined the exemption by the disease being vaccinated against rather than by the technology of the vaccine itself. It therefore extended the safety history of conventional flu vaccines to a platform never before licensed for influenza.
Moderna did use saline once, in its small first-in-human study, to evaluate safety and immune response. It never tested mFLUSIVA’s clinical efficacy against saline. Not once. Every efficacy trial compared mFLUSIVA with another influenza vaccine, and the early saline-controlled safety study was never repeated at Phase 3 scale.
That distinction matters because Kennedy’s announced policy was supposed to answer precisely the safety question an active comparator cannot fully answer: what does a new vaccine add compared with an inert control? For mFLUSIVA, FDA never obtained that answer at scale.
Kennedy promised placebo-controlled testing for new vaccines. His department then treated the first mRNA influenza vaccine as though it were not new, because influenza vaccines themselves are old. FDA licensed a novel vaccine platform under the inherited safety reputation of products built with different technology.
[quote] A Standard Announced, and an Exemption That Does Not Fit
On May 1, 2025, the Department of Health and Human Services told the Washington Post that, under Secretary Kennedy, all new vaccines would undergo placebo-controlled safety testing before licensure. HHS called it a “radical departure” from previous practice (HHS 2025).
A placebo-controlled trial compares the vaccine with an inert injection, usually saline. An active-controlled trial compares it with another vaccine. The distinction determines what can be measured. Against saline, the adverse-event rate attributable to the vaccine can emerge against a relatively clean baseline. Against another vaccine, the trial measures only the difference between two products. If both produce the same adverse event at elevated rates, the comparison can obscure it.
HHS never issued the policy as a regulation or formal guidance. It announced it to reporters and immediately carved out an exemption. The department declined to specify exactly which vaccines the new requirement covered, but told the Post that influenza vaccines were excluded because they had been “tried and tested for more than 80 years.”
That exemption does not fit mFLUSIVA.
The 80-year safety record belongs to conventional influenza vaccines. mFLUSIVA is the first licensed influenza vaccine built on an mRNA-lipid nanoparticle platform. The influenza antigen is familiar; the technology used to deliver the genetic instructions for producing it is not. HHS defined the exemption by the disease being vaccinated against rather than by the technology of the vaccine itself. It therefore extended the safety history of conventional flu vaccines to a platform never before licensed for influenza.
Moderna did use saline once, in its small first-in-human study, to evaluate safety and immune response. It never tested mFLUSIVA’s clinical efficacy against saline. Not once. Every efficacy trial compared mFLUSIVA with another influenza vaccine, and the early saline-controlled safety study was never repeated at Phase 3 scale.
That distinction matters because Kennedy’s announced policy was supposed to answer precisely the safety question an active comparator cannot fully answer: what does a new vaccine add compared with an inert control? For mFLUSIVA, FDA never obtained that answer at scale.
Kennedy promised placebo-controlled testing for new vaccines. His department then treated the first mRNA influenza vaccine as though it were not new, because influenza vaccines themselves are old. FDA licensed a novel vaccine platform under the inherited safety reputation of products built with different technology.[/quote]