ARCT-2301

ARCT-2301 is a self-amplifying mRNA (sa-mRNA) vaccine, also known as a replicon vaccine, developed by Arcturus Therapeutics in partnership with CSL Seqirus. It is designed to protect against COVID-19 by encoding the SARS-CoV-2 spike protein. The sa-mRNA technology incorporates a viral replicase that allows the mRNA to self-replicate within host cells, leading to sustained antigen expression and potentially requiring lower doses than conventional mRNA vaccines. ARCT-2301 is a bivalent formulation and has been updated to target variants such as Omicron JN.1. In August 2025, Meiji Seika Pharma received manufacturing and marketing approval for the JN.1-targeted version of the vaccine in Japan, with plans for commercial supply to begin in late 2025.

Brand names

KOSTAIVE

Other names

KOSTAIVE Bivalentself-amplifying mRNA COVID-19 vaccinesa-mRNA COVID-19 vaccinereplicon COVID-19 vaccine