French vaccine company Valneva SE (Nasdaq:VALN) (Euronext Paris:VLA) on Monday announced positive results from two Phase 2 trials of S4V2, its tetravalent bioconjugate vaccine candidate targeting shigellosis.

The studies demonstrated a favourable safety profile, encouraging immune responses and preliminary evidence of vaccine efficacy.

The Phase 2 infant trial, conducted in Kenya among 110 nine-month-old infants, showed that S4V2 was well tolerated at both evaluated dose levels. The vaccine generated statistically significant antibody responses against all four targeted Shigella serotypes, with levels remaining above baseline six months after the second dose.

In a separate Phase 2 controlled human infection model (CHIM) trial involving approximately 120 healthy adults in the United States, S4V2 met its primary endpoint, demonstrating a statistically significant reduction in shigellosis caused by the Shigella sonnei serotype compared with placebo.

Further analysis of the CHIM trial's efficacy and immunogenicity data remains ongoing. Valneva is reviewing the complete datasets from both trials to determine the next development steps, including dose selection and vaccination scheduling for the potential first-in-class vaccine candidate.

The infant trial (S4V02) received funding from the Gates Foundation.