Immunogenicity and safety of self-amplifying mRNA COVID-19 vaccine (ARCT-2303), with or without co-administration of seasonal inactivated influenza vaccine in adults: a phase 3, randomised, controlled, observer-blind, multicentre study.

ABSTRACT:

Background

A recently licenced self-amplifying mRNA (sa-mRNA) COVID-19 vaccine induces a robust, broad, and long-lasting immune response, extending the arsenal of efficacious COVID-19 countermeasures. We ran a clinical study to assess the benefits of vaccine strain update and the feasibility of co-administration with influenza vaccines.

Methods

Between March 27, 2024 and April 10, 2025, we performed a randomised, observer-blind, placebo-controlled, phase 3 study with 1499 adult participants to compare immune responses of sa-mRNA vaccine, encoding spike glycoprotein of the XBB.1.5 subvariant (ARCT-2303), with vaccine encoding the ancestral strain (ARCT-154), as measured by geometric mean titres of neutralising antibodies and SARS-CoV-2 neutralising antibody seroconversion rat

SUBMITTER: Giles ML 

PROVIDER: S-EPMC12396474 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature