The difference with Spikevax, the previous vaccine, is that the new mRNA encodes only the immunodominant regions of the SARS-CoV-2 spike protein—the receptor-binding domain (RBD) and the N-terminal domain rather than the full-length spike used in currently authorised mRNA vaccines.
Basically why encode the whole protein when encoding the parts targeted by the immune system is enough.
This allows for a much smaller dose 10µg vs 50µg while eliciting more antibodies.
The plots are not very readable though so here are the result for the relative antibodies for mNEXSPIKE (10 µg) vs Spikevax (50 µg) with the confidence intervals
Age 18–64 years: 1.3x [1.1–1.5]
Age ≥50 years: 1.4x [1.2–1.7]
Age ≥65 years: 1.8 (1.4–2.2)
That’s very good.
Lancet Paper (Open Access): Efficacy, immunogenicity, and safety of a next-generation mRNA-1283 COVID-19 vaccine compared with the mRNA-1273 vaccine (NextCOVE): results from a phase 3, randomised, observer-blind, active-controlled trial
