Long-Term Immunogenicity of the Norovirus GI.1/GII.4 Bivalent Virus-like Particle (VLP) Vaccine (NoV Vaccine) in Adults

The drug being tested in this study is called NoV vaccine. NoV vaccine is being tested for
protection against acute gastroenteritis (AGE) due to norovirus.

The study will enroll maximum of 575 participants. Participants who previously received NoV
vaccine in studies NOR-107, NOR-210 and NOR-204 will be enrolled. Participants from study
NOR-107 will enter the study at the time of their 3rd year post-primary vaccination, and from
studies NOR-210 and NOR-204, at their 2nd year post-primary vaccination. The duration of
participation in the study will be different for each participant.

This multi-center trial will be conducted in Belgium and the United States. The overall time
to participate in this study is maximum 5 years after primary NoV vaccination. Participants
will have a maximum of 4 visits over 3 years.

Inclusion Criteria:

1. Male and female participants who previously received at least 1 dose of NoV vaccine in
trials NOR-107, NOR-210 and NOR-204, have baseline and post-vaccination data, and completed
the primary vaccination trial protocol as initially described.

Exclusion Criteria:

1. Participation in any clinical trial is allowed, on condition that no investigational
product is administered within 30 days prior to blood sampling.

2. In the opinion of the investigator, the participant is not medically eligible to
provide blood specimens.

3. Individuals with behavioral or cognitive impairment or psychiatric disease that, in
the opinion of the investigator, may interfere with the participant's ability to
participate in the trial.