Vaxart Announces Positive Results for Its Bivalent Norovirus Vaccine Candidate in Lactating Mothers

Antibody rise observed in lactating mothers and in their breast milk

Long-term goal is to provide protection to infants through passive antibody transfer

SOUTH SAN FRANCISCO, Calif., April 30, 2024 (GLOBE NEWSWIRE) -- Vaxart, Inc. (Nasdaq: VXRT) today announced that it has completed the topline analysis for the Phase 1 clinical trial evaluating Vaxart’s oral pill bivalent norovirus vaccine candidate.

The trial was focused on lactating mothers. Antibodies to norovirus rose on average 4.0 fold for the G1.1 virus strain and 6.0 fold for the GII.4 virus strain in the breast milk of lactating mothers who received the Vaxart vaccine candidate in the high dose group. There were no vaccine-related serious adverse events (SAEs) and no dose-limiting pharmacotoxicity.

“This is an important step forward as we drive toward a vaccine candidate that may make it possible for mothers to protect their children against this highly contagious – and potentially lethal – virus. It can be difficult to immunize the youngest of children mucosally because the immune system is still developing. Passive transfer of antibodies from mothers to infants via breast milk is an innovative approach to potentially improve infection resistance in infants,” said Dr. James F. Cummings, Vaxart’s Chief Medical Officer. “We would like to thank the study subjects for their participation in this novel and important clinical trial.”

There is no approved vaccine against norovirus, which sickens approximately 21 million people in the United States each year, including the 15% of children under age 5 who contract norovirus annually. Approximately 3 million sets of parents are forced by this virus to miss work – approximately 2.2 days on average – to care for their children. The annual disease burden from norovirus is $10.6 billion in the United States alone.

Globally, norovirus has become the leading cause of pediatric gastroenteritis in health care settings in countries that have adopted a rotavirus vaccine program.¹ Pediatric deaths in the United States due to norovirus are rare, but they are much more common in the developing world.

This Phase I trial was conducted in South Africa (trial #20230307), and partially funded by the Bill & Melinda Gates Foundation. More complete results, including other immunogenicity measures, will be reported in a future scientific manuscript.

About the VXA-NVV-108 Clinical Trial

This Phase 1, multicenter, randomized, double-blind, placebo-controlled single dose, dose-ranging study is designed to evaluate the safety, tolerability, and immunogenicity of orally administered bivalent GI.1/GII.4 norovirus vaccine in healthy lactating females 18-43 years of age. The study enrolled 76 subjects at five sites in South Africa. Subjects were randomized into high- or medium-dose vaccine (N=30 for each arm) or placebo (N=16). The primary endpoint results were: