An investigational sa-mRNA COVID-19 booster vaccine developed by Arcturus Therapeutics has shown promising results in a phase 1/2 trial. The vaccine demonstrated long-lasting protection against multiple COVID-19 variants, including the D614G variant, and induced a robust neutralizing immune response.
The trial included 36 adult participants who had previously received approved COVID-19 mRNA vaccines as a primary series. The participants were randomized to receive a booster dose of one of three sa-mRNA vaccines: ARCT-021, ARCT-154, or ARCT-165. These vaccines encoded the SARS-CoV-2 full-length S glycoprotein of different strains.
The results showed that all three vaccines induced a robust neutralizing immune response against the D614G variant. The ARCT-154 vaccine, in particular, demonstrated a broad, cross-neutralizing immune response that lasted up to one year without the need for further boosting. Similar trends were observed for other variants, including Beta, Delta, and various Omicron sub-lineages.
The adverse events reported after vaccination were mild to moderate and resolved quickly. The rates of related or severe adverse events were low.
Arcturus Therapeutics believes that their sa-mRNA vaccine platform can offer improvements in the duration and breadth of protection against new and emerging COVID-19 variants. The company is in an exclusive partnership with CSL Seqirus, CSL’s vaccine subsidiary, in developing vaccines against COVID-19 and influenza.