Safety & Immunogenicity Study of Ad5 Based Oral Norovirus Vaccines

VXA-NVV-103 is a phase 1B Randomized, Double-Blind, Placebo-Controlled, Multi-Center Safety and Immunogenicity Study of Adenoviral-vector Based Oral Norovirus Vaccines Expressing GI.1 or GII.4 VP1 with Monovalent or Bivalent Dosing in Healthy Adult Volunteers. The study consists of 2 parts with will enroll 86 subjects: Part 1 - Double Blind Period: Post confirmation of eligibility subjects will be randomized in a double-blinded manner to one of four treatment arms. Treatment Group 1 will contain an open-label sentinel group of 6 subjects to be enrolled prior to initiation of subsequent treatment groups. After review of the safety data and confirmation the dose is well tolerated through Study Day 8, the rest of the study will proceed in a double-blinded, randomized fashion. The 6 sentinel subjects will not be part of the 16 subjects in Treatment Group 1 to be enrolled in the double-blinded placebo-controlled cohort; randomization will be 1:1:2:1 for Treatment Groups 1 through 4 respectively. Study Design and Vaccine Groups 1. Monovalent GII.4 VXA-G2.4-NS (6 sentinels / 16 randomized) 2. Monovalent GI.1 VXA-G1.1-NN (16 randomized) 3. Bivalent GII.4/GI.1 VXA-G2.4-NS + VXA-G1.1-NN (32 randomized) 4. Placebo Tablets no vaccine (16 randomized) Subjects will be followed for \~4 weeks post vaccination for safety and immunogenicity. The study database will be locked post completion of Day 29 visits. Part 2 will consist of an open label booster vaccination for the bivalent treatment group \~4 months post initial vaccination. Subjects will be followed for safety and immunogenicity for \~4 weeks post the boost. All subjects will be followed for long term safety for 1 year post initial vaccination.