Authors
Antoinette A Pragalos, Filippo Pacciarini, Hongfan Jin, Terri Hopkins, Ye Zhang, Roberto Bugarini, Xuexuan Liu, Brian M Sullivan, Carole Verhoeven, Igor Smolenov
Published in
Nature communications. Volume 17. Issue 1. Sep 24, 2026. Epub Sep 24, 2026.
Abstract
Avian influenza poses a persistent pandemic threat, yet traditional vaccines face production delays. Self-amplifying mRNA (sa-mRNA) technology offers potential advantages, including rapid development, dose sparing, and enhanced, durable immunity. We evaluated ARCT-2304, a bicistronic sa-mRNA vaccine encoding H5N1 hemagglutinin (HA) and neuraminidase (NA), in a Phase 1 randomized, observer-blind trial (NCT06602531). Healthy adults (N = 212) received two doses of ARCT-2304 (1.5, 5, or 12 mcg) or control/placebo on a 4- or 8-week schedule. Primary outcomes evaluated safety and reactogenicity (solicited/unsolicited/serious adverse events [AEs]) and immunogenicity (HA inhibition and NA enzyme-linked lectin assays 28 days post-second dose). Immunogenicity results were benchmarked using serum from a prior study supporting licensure of an H5N1 vaccine. ARCT-2304 was well-tolerated, displaying mostly mild-to-moderate, transient, dose-dependent solicited AEs, with no safety concerns identified. Two doses elicited robust HA and NA humoral responses. An 8-week interval yielded higher magnitude and greater durability than a 4-week schedule, with neutralizing and anti-NA antibodies remaining significantly elevated 6-7 months post-second dose. ARCT-2304 also induced dose-dependent, Th1-polarized T-cell responses peaking at Day 29. These findings support advancing sa-mRNA platforms for pandemic influenza preparedness.
PMID:
42928290
Bibliographic data and abstract were imported from PubMed on 26 Oct 2026.
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