On Feb. 5, 2024, CSL and and Arcturus Therapeutics announced the results of a follow-up analysis of a Phase 3 study evaluating a booster dose of ARCT-154 , the world’s first approved self-amplifying messenger RNA (sa-mRNA) COVID-19 vaccine, compared to a conventional mRNA COVID-19 vaccine. ARCT-154 was administered at one-sixth the dose of Comirnaty^® (5 μg vs 30 μg, respectively).

This randomized, double-blind, active-controlled study, conducted at 11 sites in Japan assessed the immunogenicity of ARCT-154 and Comirnaty^® at one, three- and six-months post-booster.

The new analysis at 6 months post-vaccination showed that ARCT-154 induces a longer immune response as compared to Comirnaty for both the original Wuhan strain and Omicron BA.4/5 variant and an advantage in antibody persistence.