Vaxart Inc., of South San Francisco, said it started a phase I trial of an oral norovirus tablet vaccine. The randomized, double-blind, placebo-controlled, dose-ranging study will assess the safety and immunogenicity of the VP1 protein-based vaccine in 66 healthy adult volunteers. Study participants will be followed for 12 months for safety, and a broad range of systemic and local immune responses will be evaluated at multiple time points over the study.