GSK Advances Shigella Vaccine Program With Completed Phase 2 Trial in African Infants

GlaxoSmithKline (GSK) announced an update on their ongoing clinical study.

Study Overview
GlaxoSmithKline (GSK) is running a Phase 2 trial titled “A Phase 2 Single-Blind, Randomized, Controlled, Single Center Study to Assess the Immunogenicity and Safety of a 2-Dose Schedule With GVGH altsonflex1-2-3 Vaccine in African Infants (H06_02TP).” The study looks at how well a new two-dose Shigella vaccine schedule triggers an immune response and how safe it is in infants in Africa. Shigella is a major cause of severe diarrhea in young children, especially in low- and middle-income countries, so a simple and effective vaccine schedule could have strong public-health value and support GSK’s broader vaccines portfolio.

Intervention/Treatment
The study tests three dose levels of GSK’s experimental Shigella vaccine, altSonflex1-2-3, given as a two-dose series. Each dose is given by injection and is designed to prevent Shigella-related diarrhea. The study compares these doses with a control group that receives approved vaccines for typhoid (TYPHIBEV), a combination pediatric vaccine (Infanrix hexa), and a measles-rubella vaccine (MR-VAC). This setup helps show how the new Shigella vaccine performs alongside standard childhood immunizations.

Study Design
This is an interventional, randomized, controlled trial. Infants are randomly assigned to one of four groups in parallel: three groups receive different doses (A, B, or C) of the altSonflex1-2-3 vaccine plus MR-VAC, and one group receives the control vaccines (TYPHIBEV, Infanrix hexa, and MR-VAC). The trial is single-blind, meaning the participants’ caregivers do not know which study vaccine the child receives, helping reduce bias in reported outcomes. The main goal is prevention of shigellosis, with safety and immune response as primary measures.

Study Timeline
The study was first submitted on October 25, 2024, marking the formal start of regulatory tracking and visibility for investors and stakeholders. Although specific primary and final completion dates are not listed here, the status is “Completed,” indicating that planned dosing and follow-up have finished and data are in the analysis phase. The record was most recently updated on January 28, 2026, signaling fresh activity such as data cleaning, analysis, or preparation for publication and potential regulatory discussions.

Market Implications
For investors, this update underscores GSK’s continued push in vaccines targeting high-burden infectious diseases in emerging markets. A safe and effective Shigella vaccine with a practical two-dose schedule could strengthen GSK’s pediatric vaccine franchise, complement products like Infanrix hexa, and support long-term revenue diversification beyond traditional markets. While near-term earnings impact is limited until later-stage data and regulatory paths are clear, successful Phase 2 outcomes would improve the value of GSK’s early- and mid-stage pipeline and support sentiment around its innovation story. Competitors in enteric and pediatric vaccines, including major players like Sanofi, Pfizer, and regional manufacturers, are active in adjacent areas, but Shigella remains relatively under-served, giving GSK a chance to secure a leading position if efficacy and safety are confirmed and pricing is competitive. The recent update, together with a completed status, should be seen as a modest positive signal for GSK’s longer-term vaccines strategy.

The study is now completed and recently updated, with further details available on the ClinicalTrials portal.

To learn more about GSK’s potential, visit the GlaxoSmithKline drug pipeline page.