Safety. Moderna reported no new safety concerns for mRNA-1083 compared with the individual vaccines. Overall local and systemic adverse reactions were similar to those observed in the Spikevax COVID-19 group in the trial. Severity of the majority of adverse reactions was assessed as grade 1 or 2; grade 3 solicited local or solicited systemic reactions were reported in less than 4% of participants aged 50 years and older. Phase 3. Moderna expects to begin the phase 3 trial of mRNA-1083 before the end of the year, according to the statement, and is targeting potential regulatory approval for the combination vaccine in 2025.