Safety and Immunogenicity of Norovirus Bivalent Virus-Like Particle Vaccine in Healthy Adults

The vaccine being tested in this study is called norovirus GI.1/GII.4 bivalent virus-like particle (VLP) vaccine adjuvanted with or without monophosphoryl lipid A (MPL) and with aluminum hydroxide. The norovirus vaccine is being tested to provide additional safety and immunogenicity data to enable the vaccine to be further developed. This study will look at the side effects in people who take different formulations of the norovirus vaccine. The study will enroll approximately 450 participants. Participants will be randomly assigned (by chance, like flipping a coin) to one of the 3 treatment groups-which will remain undisclosed to the participant and study doctor during the study (unless there is an urgent medical need): * one dose of GI.1/GII.4 (15 µg/50 µg) adjuvanted with MPL (50 µg) and aluminum hydroxide (500 µg) on Day 1 followed by one dose of GI.1/GII.4 (15 µg/15 µg) adjuvanted with aluminum hydroxide (500 µg) (without MPL) on Day 365 * one dose of GI.1/GII.4 (50 µg/50 µg) adjuvanted with MPL (50 µg) and aluminum hydroxide (500 µg) on Day 1 followed by one dose of GI.1/GII.4 (15 µg/15 µg) adjuvanted with aluminum hydroxide (500 µg) (without MPL) on Day 365 * one dose of Saline Placebo (dummy inactive injection) - this is a liquid that has no active ingredient-on Day 1 + GI.1/GII.4 (15 µg/15 µg) adjuvanted with aluminum hydroxide (500 µg) (without MPL) as primary vaccination on Day 365 All participants will be administered vaccine or placebo on Day 1 of the study and will receive a vaccination dose (reduced antigen content) of the norovirus vaccine on Day 365. Participants will be asked to record any symptoms that may be related to the vaccine or the injection site in a diary card for 7 days after each vaccination. This multi-center trial will be conducted in the United States. The overall time to participate in this study is up to 18 months. Participants will make 11 visits to the clinic including a follow-up visit 6 months after the last dose of study medication.