Modified mRNA Influenza Vaccine Superior to Inactivated Influenza Vaccine

FRIDAY, Nov. 21, 2025 (HealthDay News) — A quadrivalent nucleoside-modified messenger RNA (modRNA) influenza vaccine is superior to a licensed inactivated quadrivalent influenza vaccine, according to a study published in the Nov. 20 issue of the New England Journal of Medicine.

David Fitz‑Patrick, M.D., from East-West Medical Research Institute in Honolulu, and colleagues randomly assigned healthy adults aged 18 to 64 years to receive either a quadrivalent modRNA influenza vaccine (modRNA group) or a licensed inactivated quadrivalent influenza vaccine (control group) during the 2022 to 2023 influenza season in a phase 3 trial. Relative efficacy, defined by the reduction in the percentage of participants with laboratory-confirmed influenza associated with influenza-like illness at least 14 days after vaccination with the modRNA vaccine, as compared with the control vaccine, was the primary end point.

The study included 18,476 participants: 9,225 and 9,251 were randomly assigned to receive the modRNA vaccine and control vaccine, respectively. The researchers found that the relative efficacy of the modRNA vaccine was 34.5 percent against influenza-like illness compared with the control vaccine, on the basis of 57 and 87 cases in the modRNA and control groups, respectively; this finding met the criteria for noninferiority and superiority. The noninferiority of the antibody response on hemagglutination inhibition assay was seen for influenza A, but not influenza B, strains. Both vaccine groups had primarily mild or moderate reactogenicity, which was reported more frequently in the modRNA group.

“The modRNA platform offers promise for the development of influenza vaccines and may improve upon existing products,” the authors write.

The study was funded by Pfizer.

Abstract/Full Text

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