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

Core Insights - Vaxart, Inc. announced the publication of complete data from a Phase 2b challenge study of its first-generation oral pill norovirus vaccine candidate, which met five of its six primary endpoints, demonstrating safety, efficacy, and immunogenicity [1][4] - Machine learning analyses identified functional blocking antibody and fecal IgA as robust correlates of protection, which will inform the development of Vaxart's second-generation norovirus vaccine candidate currently in a Phase 1 clinical trial [1][2] Study Details - The Phase 2b challenge study enrolled 165 healthy adults, randomized to receive either the vaccine candidate targeting norovirus GI.1 genotype or a placebo, with a primary objective to determine vaccine efficacy against norovirus infection and gastroenteritis [3] - Key findings included a 30% relative reduction in norovirus infection for the vaccine group compared to placebo (p=0.003) and a 21% relative reduction in norovirus gastroenteritis, although not statistically significant (p=0.178) [4] Immunogenicity and Safety - The vaccine significantly increased serum IgA, IgG, and norovirus-blocking antibodies (p<0.001 for all endpoints), and stimulated mucosal-homing B cells, increasing norovirus-specific antibodies in saliva, nasal lining fluid, and intestine [4] - The vaccine was reported to be safe and well-tolerated, with no serious vaccine-related events or dose-limiting toxicities, and most adverse events were mild [4] Future Development - Vaxart initiated a Phase 1 trial comparing its first- and second-generation norovirus vaccine candidates in March 2025, aiming to enhance immunogenicity and protection [1][5][6] - The company believes that a safe and effective norovirus vaccine is essential for global health and is confident in its oral pill vaccine platform [6]