Positive phase III efficacy data for mRNA 1283, the next generation COVID-19 vaccine

The Company also announced that higher efficacy was observed in adults 18 years of age and older compared to Spikevax (mRNA-1273), with a consistent trend observed in the subset of adults age 65 and older. Positive interim immunogenicity results for mRNA 1283 in this study were previously reported in March 2024.

The ongoing Phase III clinical trial (ClinicalTrials.gov Identifier: NCT05815498) is a randomized, observer-blind, active-controlled study of approximately 11,400 individuals aged 12 years and older. Half of the participants received a 10 ug dose of mRNA 1283, while the other half received a 50 ug dose of mRNA 1273 (Spikevax). Today's vaccine efficacy data are consistent with the previously announced immunogenicity results from the study, which showed that mRNA 1283 had higher neutralizing antibody responses against both Omicron BA.4/5 and ancestral SARS-CoV-2 than mRNA 1273, with the highest geometric mean titer ratios observed in adults and in the subset of participants aged 65 years and older. In the trial, mRNA 1283 was found to have a similar safety profile to Spikevax. The most commonly solicited side effects were injection site pain, fatigue, headache and myalgia.

Moderna's combination vaccine candidate against influenza and COVID-19, mRNA-1083, includes mRNA 1283. That vaccine candidate recently announced positive results in its separate Phase III trial.

Moderna plans to present the Phase III clinical data for mRNA 1283 at an upcoming conference as well as submit it for publication. The Company will also engage with regulators on the next steps for the program.