Moderna has dosed the first participant in its Phase 3 trial for mRNA-1403, an investigational norovirus vaccine. Norovirus, a contagious gastrointestinal virus, spreads through direct contact, contaminated food, and surfaces. The trial aims to enroll 25,000 participants globally to assess mRNA-1403's efficacy, safety, and immunogenicity, focusing on adults, particularly those 60 and older. Prevention measures include handwashing, thorough cooking, and surface disinfection.