A phase 3 randomized safety and immunogenicity trial of mRNA-1010 seasonal influenza vaccine in adults

Background: Messenger RNA (mRNA)-based influenza vaccines have the potential to improve upon limitations of current vaccine approaches to seasonal influenza. Methods: Here we report findings on the primary and secondary objectives of the safety, reactogenicity, and humoral immunogenicity of the quadrivalent mRNA vaccine, mRNA-1010, versus licensed standard-dose and high-dose quadrivalent influenza vaccines from a three-part, phase 3 clinical trial in adults aged ≥18 years (Part A), 18–64 years (Part B), and ≥ 65 years (Part C) (NCT05827978). Results: A single 50-μg dose of mRNA-1010 elicited hemagglutination inhibition titers against vaccine-matched strains that were statistically noninferior and superior to licensed standard-dose and high-dose egg-based quadrivalent vaccine comparators. Solicited adverse reactions were more frequent with receipt of mRNA-1010; adverse reactions were lower in frequency and severity among adults aged ≥65 years than younger adults. No safety concerns were identified. Conclusions: These findings support the potential benefit of mRNA-1010 as a seasonal influenza vaccine.