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VAX-A1

Development stage: Phase 1
Lead developer: Vaxcyte
Modality: Vaccines & Immunotherapeutics
Administration: Intramuscular

Overview

**VAX-A1** is Vaxcyte's investigational prophylactic, multicomponent Group A Streptococcus conjugate vaccine. It combines a modified Group A carbohydrate polyrhamnose antigen designed to remove potentially cross-reactive epitopes with three conserved *Streptococcus pyogenes* protein antigens: C5a peptidase, streptolysin O, and S. pyogenes adhesion and division protein. The vaccine is intended to induce broad, strain-independent protective immunity against Group A Strep infections, including both common and invasive disease. VAX-A1 entered a randomized, placebo-controlled Phase 1 study in healthy adults in June 2026. ([investors.vaxcyte.com](https://investors.vaxcyte.com/news-releases/news-release-details/vaxcyte-doses-first-participant-phase-1-study-evaluating-vax-a1))

Other names: VAX-A1 HighVAX-A-1 HighVAX-A 1 High

Targets

GAC^PR (Group A Streptococcus polyrhamnose cell-wall polysaccharide epitope)ScpA (Streptococcal C5a peptidase)SLO (Streptolysin O)SCP (Streptococcal C5a peptidase)

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