Safety and immunogenicity of a phase 1/2 randomized clinical trial of a quadrivalent, mRNA-based seasonal influenza vaccine (mRNA-1010) in healthy adults: interim analysis

Despite vaccine availability, influenza remains a substantial global public health concern. Here, we report interim findings on the primary and secondary objectives of the safety, reactogenicity, and humoral immunogenicity of a quadrivalent messenger RNA (mRNA) vaccine against seasonal influenza, mRNA-1010, from the first 2 parts of a 3-part, first-in-human, phase 1/2 clinical trial in healthy adults aged & GE;18 years (NCT04956575). In the placebo-controlled Part 1, a single dose of mRNA-1010 (50 & mu;g, 100 & mu;g, or 200 & mu;g) elicited hemagglutination inhibition (HAI) titers against vaccine-matched strains. In the active-comparator-controlled Part 2, mRNA-1010 (25 & mu;g, 50 & mu;g, or 100 & mu;g) elicited higher HAI titers than a standard dose, inactivated seasonal influenza vaccine for influenza A strains and comparable HAI titers for influenza B strains. No safety concerns were identified; solicited adverse reactions were dose-dependent and more frequent after receipt of mRNA-1010 than the active comparator. These interim data support continued development of mRNA-1010. Here the authors report initial findings of a phase 1 clinical trial, showing that an investigational, mRNA-based vaccine for seasonal influenza (mRNA-1010) has no safety concerns and produces immune responses in adults that are similar or higher than a licensed comparator vaccine.

Automated summary

Despite vaccine availability, influenza remains a significant global public health concern. Preliminary results from a phase 1/2 clinical trial show that mRNA-1010, a quadrivalent mRNA vaccine against seasonal influenza, is safe and elicits a strong immune response in adults. The vaccine produces higher or comparable levels of hemagglutination inhibition (HAI) antibodies compared to the licensed comparator vaccine.