Clinical trialsCompany release

Valneva's Shigella vaccine S4V2 meets primary endpoint in Phase 2 adult challenge trial

Valneva SE (VALN) · Fri 13 Nov 2026

Valneva reports positive Phase 2 data for its tetravalent Shigella candidate, with a significant efficacy signal against S. sonnei in adults and immunogenicity in Kenyan infants.

Valneva has reported positive results from two Phase 2 trials of S4V2, its tetravalent bioconjugate vaccine candidate against Shigella, the company said in an announcement dated 13 November 2026 that refers to results reported on 9 November.

The US controlled human infection trial in adults met its primary endpoint. Participants who received S4V2 had a statistically significant reduction in shigellosis caused by S. sonnei compared with those given placebo. In such trials, volunteers are deliberately exposed to the pathogen under controlled conditions to gauge protection.

The second study, in Kenya, enrolled 110 infants. Valneva says S4V2 showed a favourable safety profile and produced higher anti-LPS IgG levels than control for all four serotypes covered by the vaccine.

The company is still analysing the full datasets and will use them to decide on next development steps. The candidate already holds Fast Track designation from the US Food and Drug Administration, a status intended to speed up development and review of products for serious conditions with unmet need.

What it means for your team

  • The challenge-trial result gives a first efficacy signal for S4V2, but it covers S. sonnei only; the full datasets are still under review.
  • Infant data so far cover safety and immune response rather than clinical protection, so regulators will likely look for further evidence in the target population.
  • Fast Track status may allow more frequent FDA interaction, but Valneva has not yet announced a Phase 3 plan or filing timeline.
  • Safety teams should watch for fuller infant safety data once Valneva publishes or presents the complete results.

Company's press release (SEC filing): Valneva SE ↗

Article written by VigiEye from the official source (Valneva SE). Claims are the company's own. AI-assisted; check the source before acting.

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