Pfizer's mRNA vaccine for influenza failed when tested against the standard flu shot in a 27,000-person trial of older adults — a failure Pfizer has not announced for years.

Almost three times as many people who received the mRNA shot suffered acute respiratory failure or major kidney problems. More died, too. Overall, mRNA patients were much more likely to report side effects than those who got the standard flu shot.

But mRNA shots did not protect patients from the flu better than standard shots.

mRNA Covid jab sales have already cratered. This new failure may effectively end development of mRNA shots for respiratory viruses — and many other viruses too.

Pfizer has never publicly announced the failure of the trial.

In a statement on Halloween 2023, the company promised to release the results by the end of 20231. It did not.

Instead, in May 2025, long after its self-imposed deadline, Pfizer quietly updated the "study results" page for the trial on the clinicaltrials.gov Website with trial's results.

They reveal across-the-board failure on both safety and efficacy for the mRNA influenza shot. (I am suing Pfizer chairman Dr. Albert Bourla and director Dr. Scott Gottlieb for conspiring to violate my Constitutional rights and forcing Twitter to ban me in 2021.)

The trial included about 45,000 people, about 27,000 over 65 and 18,000 under 65. Patients were randomly chosen to receive either the standard flu shot or Pfizer's mRNA jab.2 There was no placebo arm in the trial, though there probably should have been, since many epidemiologists doubt the value of standard flu shots and a placebo arm would have shown potential safety risks even more clearly.

Older people who got mRNA shots were about 6 percent more likely to get the flu than those who got standard shots. And 49 older people who received the mRNA shot died, compared to 46 who received the flu shot.

The study also revealed a significant safety signal for the mRNAs on kidney damage. Twenty-two older patients who received the mRNA shot were diagnosed with acute kidney injury, chronic kidney disease, or end-stage renal disease, compared to nine who received the standard shot.