The Modified mRNA Influenza Vaccine Trial - Part 1

The case definitions

In November, the New England Journal of Medicine published the Efficacy, Immunogenicity, and Safety of Modified mRNA Influenza Vaccine.

This phase 3, randomised, observer-blinded trial compared a quadrivalent modified mRNA (modRNA) influenza vaccine with a licensed inactivated vaccine in healthy adults aged 18–64 during the 2022–2023 season.

So, no placebo then.

In the trial, 18,476 participants were assigned to receive either vaccine across sites in the US, South Africa, and the Philippines. The primary endpoint was the relative efficacy against laboratory-confirmed influenza-like illness at least 14 days post-vaccination, along with immunogenicity and safety.

The trial was designed and conducted by the sponsor, Pfizer, which also performed the data collection, analysis, and interpretation.

Now, if you read the conclusion, you’d think it was a done deal: The relative efficacy of the vaccine as compared with control against influenza-like illness was 34.5%.