Vaxart, Inc. announced that it has enrolled the first subject in a Phase 1b boosting regimen trial of its norovirus vaccine candidate. This study is designed to evaluate the safety and immunogenicity of various dosing intervals for Vaxart’s candidate, which is the only clinical stage norovirus oral tablet vaccine actively being developed. Norovirus is an enteric pathogen that infects epithelial cells of the small intestine. Vaxart’s VP1-based bivalent oral tablet vaccine candidate targets the norovirus GI.1 Norwalk and GII.4 Sydney strains, which are the predominant strains affecting humans. The booster regimen trial is the second of four Vaxart norovirus trials that are ongoing or are planned for 2021. Vaxart is currently administering a second booster dose to a subset of subjects who had participated in the prior Phase 1b bivalent study. The Company is also scheduled to initiate an age escalation trial in subjects over 65 years old and plans to launch a Phase 2 challenge study later this year. The Phase 1b study is designed to enroll 30 subjects aged 18 to 55 years old. Subjects will be randomized into 3 cohorts: Cohort 1 will receive the vaccine candidate on day 1 and week 4 of the study; Cohort 2 will receive the vaccine candidate on day 1 and week 8 of the study; Cohort 3 will receive the vaccine candidate on day 1 and week 12 of the study. The endpoints are safety and immunogenicity.