On Jan. 26, 2022, Moderna announced that the first participant had been dosed in the Phase 2 study of the Company’s Omicron-specific booster candidate (mRNA-1273.529). Additionally, Moderna announced the publication of neutralizing antibody data against the Omicron variant six months following a booster dose in The New England Journal of Medicine.

This extension of an earlier study planned to evaluate the immunogenicity, safety, and reactogenicity of mRNA-1273.529 as a single booster dose in adults aged 18 years and older in two cohorts: individuals who previously received the two-dose primary series of mRNA-1273 with the second dose being at least six months ago (cohort 1), or who had received the two-dose primary series and a 50 µg booster dose of mRNA-1273 with the booster dose being at least three months ago (cohort 2). Participants in both cohorts received a single booster dose of mRNA-1273.529.

Moderna expected to enroll approximately 300 participants into each cohort of this study, which was planned to be conducted at up to 24 sites in the U.S. Additionally, Moderna was evaluating the inclusion of mRNA-1273.529 in its multivalent booster program.