Vaxart Publishes Positive, Complete Data from a Phase 2b Challenge Study of its First-Generation Oral Pill Norovirus Vaccine Candidate in Science Translational Medicine

Challenge Study measured safety, efficacy against infection and symptomatic disease as well as viral shedding

Machine learning analyses identified statistically significant correlates of protection and will be incorporated into the development of Vaxart’s second-generation norovirus vaccine candidate, which is being evaluated in a Phase 1 clinical trial

Excerpt from the Press Release:

SOUTH SAN FRANCISCO, Calif., May 14, 2025 (GLOBE NEWSWIRE) — Vaxart, Inc. (Nasdaq: VXRT) today announced the publication of complete data from a Phase 2b challenge study of its first-generation oral pill norovirus vaccine candidate (NCT05212168) in Science Translational Medicine. Consistent with preliminary data reported in September 2023, the complete results show that the trial met five of its six primary endpoints and demonstrate the safety, efficacy, and immunogenicity of the vaccine candidate. Additional data included in the current publication include results from machine learning analyses that identify functional blocking antibody and fecal IgA as robust correlates of protection (CoP). These additional results will help inform the development of the Company’s second-generation oral pill norovirus vaccine candidate. Vaxart initiated a Phase 1 trial comparing its first- and second-generation norovirus vaccine candidates in March 2025.

“Challenge studies provide unique opportunities to identify correlates of protection that can be used to predict vaccine efficacy and support vaccine development,” said James F. Cummings, MD, Chief Medical Officer at Vaxart. “The application of machine learning approaches to the complete data from the Phase 2b challenge study of our first-generation oral pill norovirus vaccine candidate identified two such correlates, functional serum blocking antibody and fecal IgA. Evaluation of these endpoints will help inform our understanding and provide an early read on the potential efficacy profile of our second-generation norovirus vaccine candidate as it advances through clinical development.

The single-center, double-blinded Phase 2b challenge study enrolled 165 healthy adults, who were randomized 1:1 to receive Vaxart’s monovalent oral pill vaccine candidate targeting the norovirus GI.1 genotype or placebo. Four weeks after vaccination, subjects were challenged with GI.1 norovirus. The primary objective of the study was to determine vaccine efficacy against norovirus infection and norovirus gastroenteritis (NVG) after GI.1 NV challenge. Secondary objectives were to assess the safety and tolerability of the vaccine candidate. The ability of the vaccine candidate to modify disease severity, the quantity and duration of norovirus shedding, and a set of immunogenicity parameters also were quantified. The primary efficacy endpoints were the proportion of participants showing evidence of NVG, a composite endpoint defined as meeting one or more definitions for acute gastroenteritis (AGE) and a positive norovirus infection (detected by qPCR), and norovirus infection (detected by qPCR).

Click the button below to read the entire Press Release:

Continue Reading The Press Release