Vaxart, Inc. (NASDAQ: VXRT), a clinical-stage biotechnology company developing oral recombinant vaccines that are administered by tablet rather than by injection, today 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.

In a health economic study published in the American Journal of Preventative Medicine in January 2021, the negative economic impact to the U.S. of norovirus was estimated to be approximately $10.5 billion* annually. Annual vaccine costs with an efficacy of 75% were cost effective and cost saving at ≤$1,600 and ≤$1,300 per year, respectively, for preschool-aged children, and ≤$165 and ≤$100 per year, respectively, for older adults.

“Norovirus is a potentially fatal illness that affects around 20 million Americans annually. It has an enormous impact on young families with 15% of children under age five being infected every year in the United States,” said Andrei Floroiu, Vaxart’s chief executive officer. “The WHO designated norovirus as a priority disease for vaccine development, as it is a major public health problem with no approved vaccine available, having a multi-billion dollar annual impact in the US alone and significantly more globally.”

Sean Tucker, Ph.D., chief scientific officer of Vaxart commented, “This study will provide insight into the optimal booster timing to maximize immunogenicity and total response of our oral norovirus vaccine candidate. Additionally, the findings may provide important information into the overall dynamics of our platform technology that could guide future protocols for our other vaccine candidates, including our oral COVID-19 tablet vaccine candidate, which is estimated to enter Phase 2 clinical trials around mid-year.”

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.

VXA-NVV-105 Phase Booster Regimen 1b Trial Design

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. For more information, refer to ClinicalTrials.gov.

* Note: The $10.5 Billion annual economic impact of norovirus infections in the US includes both direct medical costs and indirect costs such as time off work, school, etc.