Safety and Immunogenicity of Norovirus GI.1/GII.4 Bivalent Virus-Like Particle Vaccine in an Elderly Population

The vaccine being tested in this study is called norovirus GI.1/GII.4 bivalent virus-like particle (VLP) vaccine adjuvanted with aluminum hydroxide (Formulation A) or adjuvanted with monophosphoryl lipid A (MPL) and aluminum hydroxide (Formulation B). Two norovirus vaccine formulations are being tested to select for further development the formulation that will generate an optimal specific antibody response that may provide protection against norovirus and is safe in a population aged 60 years and above. This study will look at side effects and the level of antibodies to norovirus formed in people who will be injected with different formulations of the norovirus vaccine candidate. The study will enroll approximately 325 patients. Participants will be randomly assigned (by chance) to one of five treatment groups. * Norovirus GI.1/GII.4 bivalent VLP vaccine (Formulation A) 1-dose, participants ≥ 60 years * Norovirus GI.1/GII.4 bivalent VLP vaccine (Formulation A) 2-dose, participants ≥ 60 years * Norovirus GI.1/GII.4 bivalent VLP vaccine (Formulation B) 1-dose, participants ≥ 60 years * Norovirus GI.1/GII.4 bivalent VLP vaccine (Formulation B) 2-dose, participants ≥ 60 years * Norovirus GI.1/GII.4 bivalent VLP vaccine (Formulation A) 1-dose, participants 18 to 49 years All participants in the age of 60 years and older will be administered either NoV vaccine (Formulation A or B) or placebo on Day 1 and NoV vaccine (Formulation A or B) on Day 29 of the study. In order to keep the treatment arms undisclosed to the patient and the doctor, those randomized to the one dose groups will receive a dose of placebo (this is a saline solution that has no active ingredient) on Day 1 followed by the NoV vaccine on Day 29. Those randomized to 2 doses with receive the NoV vaccine on Day 1 and Day 29. In case of an urgent medical need a participant can be unblinded. Adults aged 18 to 49 will receive placebo on Day 1 followed by NoV vaccine Formulation A on Day 29. Participants will be asked to record any reactions/ symptoms that may be related or not to the vaccine in a diary card for 28 days after each vaccination. This multi-center trial will be conducted in the United States of America. The overall time to participate in this study is up to 393 days. Participants will make multiple visits to the clinic including a final follow-up visit on Day 393.