On Dec. 10, 2020, Moderna announced that the first adolescent participants had been dosed in the Phase 2/3 study of mRNA-1273, the Company’s vaccine candidate against COVID-19, in adolescents ages 12 to less than 18. The study was conducted in collaboration with the Biomedical Advanced Research and Development Authority.

This randomized, controlled Phase 2/3 study will evaluate the safety, reactogenicity and immunogenicity of two vaccinations of mRNA-1273 given 28 days apart. The Company intends to enroll 3,000 adolescent participants in the U.S. ages 12 to less than 18 years. Each participant was assigned to receive a placebo or a 100 μg dose at both vaccinations.

Participants were followed through 12 months after the second vaccination. Vaccine effectiveness was either inferred through achieving a correlate of protection (if established) or through immunobridging to the adult population. Evaluation of vaccine safety and reactogenicity was also a primary endpoint of the study.

mRNA-1273 is an mRNA vaccine against COVID-19 encoding for a prefusion stabilized form of the Spike (S) protein, which was co-developed by Moderna and investigators from NIAID’s Vaccine Research Center. The first clinical batch, which was funded by the Coalition for Epidemic Preparedness Innovations, was completed on February 7, 2020 and underwent analytical testing; it was shipped to the NIH on February 24, 42 days from sequence selection.

The first participant in the NIAID-led Phase 1 study of mRNA-1273 was dosed on March 16, 63 days from sequence selection to Phase 1 study dosing. On May 12, the FDA granted mRNA-1273 Fast Track designation. On May 29, the first participants in each age cohort: adults ages 18-55 years (n=300) and older adults ages 55 years and above (n=300) were dosed in the Phase 2 study of mRNA-1273. On July 8, the Phase 2 study completed enrollment.