Vaccine Info

VXA‑G1.1-NN Norovirus Vaccine

Authored by


VXA-G1.1-NN is an E1/E3-deleted replication-defective Adenovirus serotype 5 vaccine vector.

The vaccine vector encodes for a full-length VP1 (major capsid protein) gene from Norovirus GI.1 Norwalk.


VXA-G1.1-NN is an Oral Vaccine Candidate Tablet indicated for the prevention of noroviral gastroenteritis caused by Norovirus GI.1.


VXA-G1.1-NN Oral Vaccine Tablets will be orally administered in multiple doses.  The number of tablets is being evaluated in the clinical trial.

Norovirus is a pathogen that infects the small intestine, Vaxart believes a vaccine that produces mucosal antibodies locally in the intestine, in addition to systemic antibodies that circulate in the blood, may better protect against norovirus infection than an injectable vaccine.


May 30, 2018: Vaxart has completed two Phase 1 clinical trials with its monovalent oral tablet vaccine based on the GI.1 norovirus strain.

The norovirus tablet vaccine was well tolerated and generated broad systemic and mucosal immune responses.

In the recently completed clinical Phase 1b dose-optimization study in healthy adults, in which Vaxart evaluated four different dosing regimens, all vaccine recipients (100%) in the high-dose group responded as measured by a significant increase in norovirus specific B cells of both IgA and IgG subtypes. 

In the same group, there was at least a two-fold increase of norovirus specific antibody titers in serum in more than 90% of recipients 56 days after dosing.

February 2019: In the first half of 2019 Vaxart initiated a Phase 1 trial of its bivalent norovirus vaccine candidate designed to assess safety and immunogenicity.

August 2019: Vaxart entered into an agreement with Lonza Houston to supply vaccine for the planned Phase 2 bivalent norovirus study in 2020.

Clinical Trial NCT02868073: Phase 1 Placebo-controlled, Randomized Trial of an Adenoviral-vector Based Norovirus Vaccine

  • The Phase 1 study will enroll 66 subjects in four cohorts. All subjects will receive a single administration of VXA-G1.1-NN at a low dose, a high dose or placebo.
  • Two sentinel groups will enroll 3 subjects each in an open-label manner (Cohorts 1 and 3) to receive VXA-G1.1-NN prior to enrolling either of the randomized, controlled cohorts (Cohorts 2 and 4).
  • Within the double-blinded Cohorts (2 and 4), placebo subjects will receive the same number of tablets as the vaccine subjects in that Cohort.
  • Subjects will be enrolled and dosed in the low dose groups prior to initiation of dosing in the high dose group.
  • Cohort 1: 3 subjects at low dose Cohort 2: 20 subjects at low dose and 10 placebo Cohort 3: 3 subjects at high dose Cohort 4: 20 subjects at low dose and 10 placebo
  • Subjects will be followed for 28 days post vaccination for preliminary immunogenicity. Subjects will continue to be followed for 1 year post-vaccination for long term safety.

Clinical Trial NCT03125473: Dose-Optimization Trial of VXA-G1.1-NN in Healthy Volunteers

  • This Phase 1 study will enroll approximately 60 subjects in four cohorts of 15 subjects each. The cohorts may be enrolled and run in parallel or overlap; they do not have to run sequentially. The dosing for each cohort will be as follows:
    • Cohort 1: Multiple low dose on Days 1 and 8 Cohort 2: Multiple low dose on Days 1, 3 and 5 Cohort 3: Multiple low dose on Days 1 and 29 Cohort 4: Multiple high dose on Days 1 and 29
  • All subjects receiving study drug will have safety and immunogenicity assessments completed through Study Day 57 following their initial vaccination. Subjects may also be evaluated for persistent immunogenicity at Day 180 and will be followed for safety for 12 months following initial vaccination (Study Day 365).

Clinical Trials

No clinical trials found