On Sept. 3, 2021, Moderna announced that it had submitted for a conditional marketing approval (CMA) with the European Medicines Agency (EMA) for the evaluation of a booster dose of the Moderna COVID-19 vaccine (mRNA-1273) at the 50 ﾵg dose level.

The Phase 2 study of mRNA-1273 was amended to offer a booster dose of mRNA-1273 at the 50 µg dose level to interested participants 6 months following their second dose (n=344). Neutralizing antibody titers had waned significantly prior to boosting at approximately 6 months. A booster dose of mRNA-1273 at the 50 µg dose level boosted neutralizing titers significantly above the Phase 3 benchmark. After a third dose, a similar level of neutralizing titers was achieved across age groups, notably in older adults (ages 65 and above). The safety profile following dose 3 was similar to that observed previously for dose 2 of mRNA-1273. These data will be submitted to a peer-reviewed publication.

An additional analysis showed that a booster dose of mRNA-1273 at the 50 µg dose level induced robust antibody responses and significantly increased geometric mean titers (GMT) for all variants of concern including Beta (B.1.351) by 32- fold, Gamma (P.1) by 43.6-fold and Delta (B.1.617.2) by 42.3-fold.