Moderna, Inc. released data from its phase III trial of mRNA-1283, an investigational next-generation COVID-19 vaccine. The trial has met its primary efficacy endpoint, demonstrating noninferior vaccine efficacy against COVID-19 compared with Spikevax. The company also announced that higher efficacy was observed in adults aged 18 years and older compared with Spikevax (mRNA-1273), with a consistent trend observed in the subset of adults aged 65 years and older. Positive interim immunogenicity results for mRNA-1283 in this study were previously reported in March 2024.

Stéphane Bancel, CEO of Moderna, stated, “We are very pleased that mRNA-1283 has now met its primary vaccine efficacy endpoint in Phase 3 and showed higher efficacy in adults compared to Spikevax. With five vaccine programs that have achieved positive Phase 3 results, Moderna’s platform is consistently demonstrating its ability to address significant unmet needs in public health.”

The ongoing phase III clinical trial is a randomized, observer-blind, active-controlled study of nearly 11,400 individuals aged 12 years and older. In this trial, 50% of the participants received a 10-mcg dose of mRNA-1283, while the other one-half received a 50-mcg dose of mRNA-1273 (Spikevax).

The recent 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 greatest geometric mean titer ratios observed in adults and in the subset of participants aged 65 years and older.

In the trial, mRNA-1283 was discovered to have a comparable safety profile with Spikevax. The most commonly reported adverse effects were injection site pain, fatigue, headache, and myalgia.

Moderna’s combination vaccine candidate against influenza and COVID-19, mRNA-1083, includes mRNA-1283, which recently yielded positive results in its separate phase III trial. Moderna plans to present the phase III clinical data for mRNA-1283 at an upcoming conference and submit them for publication. The company will also engage with regulators on the program’s next steps.

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