Norovirus Bivalent-Vaccine Efficacy Study

Inclusion Criteria

To be eligible to participate in this study, a subject must meet the following criteria:

• Signed informed consent.
• Age 18 to 50 years (e.g., not reached their 50th birthday).
• Good general health as determined by a screening evaluation within 45 days of randomization.
• Expressed interest, availability, and understanding to fulfill the study requirements including measures to prevent Norovirus contamination of the environment and spread of infection and illness to the community. The prospective subjects must pass (≥70 % correct answers) a written examination on all aspects of the study before enrollment.
• Available to return for follow-up visits following discharge from the inpatient unit and able to deliver stool specimens to the investigative site promptly with no plan to move within the duration of the study.
• Female subjects must be of non-childbearing potential, or if of childbearing potential (as determined by the investigator) must be practicing abstinence or using an effective licensed method of birth control (e.g. oral contraceptives; diaphragm or condom in combination with contraceptive jelly, cream, or foam; intrauterine contraceptive device, or Depo-Provera; skin patch; vaginal ring or cervical cap) for 30 days prior to vaccination and must agree to continue such precautions during the study and for 60 days after the Challenge visit. Male subjects must agree not to father a child from the day of vaccination until 60 days after the Challenge visit.
• Have a serum antibody titer of ≤1:1600 to the GII.4 Norovirus challenge strain as measured by Immunoglobulin G (IgG) P Particle Enzyme-Linked Immunosorbent Assay (ELISA.)
• Demonstrated to be H Type 1 secretor positive by Histoblood Group Antigen (HBGA) binding assay of their saliva test. [This saliva test may be done at anytime prior to enrollment and does not need to be repeated.]
• Negative serology for hepatitis C antibody, Human Immune Deficiency Virus (HIV) antibody, hepatitis B surface antigen, and Rapid Plasma Reagin (RPR).
• Agrees not to participate in another clinical trial with an investigational product for the duration of the study (12 months after the last dose of study vaccine or placebo i.e. 393 days).

Exclusion Criteria

To be eligible to participate in this study, a subject must NOT meet any of the following criteria:

• Living with or having daily contact with children age 5 years or less or a woman known to be pregnant. This includes significant contact at home, school, day-care, or equivalent facilities.
• Nursing mother.
• Living with or having daily contact with childcare workers.
• Living with or having daily contact with elderly persons aged 70 years or more, or infirmed, diapered individuals, persons with disabilities or incontinent persons. This includes work or visits to nursing homes and day-care or equivalent facilities.
• History of any gastroenteritis suggestive of Norovirus illness since screening serum antibody IgG P Particle ELISA testing was done.
• History of any gastroenteritis within the past 2 weeks.
• History of chronic functional dyspepsia, chronic gastroesophageal reflux disease, peptic ulcer disease, gastrointestinal hemorrhage, gall bladder disease, inflammatory bowel disease, irritable bowel syndrome, frequent diarrhea, chronic constipation, malabsorption, maldigestion, major Gastrointestinal (GI) surgery, or diverticulitis anytime during the subject's lifetime or any other chronic GI disorders that would interfere with interpretation of symptoms or evaluation during the study.
• Routine use of medication other than oral contraceptive agents, anti-hypertensives, anti-depressants, vitamins and minerals. The use of any other medications should be discussed with the Sponsor and/or Central Safety Monitor (CSM).
• History of any of the following medical illnesses:
• Immunosuppression (disease or treatments that may affect immune system function)
• Diabetes (including gestational