Phase 4 Study To Assess The Safety Of Vivotif At Different Release Titers Among Travelers

This is a multicenter (at travel clinics), phase 4 observational prospective cohort study in healthy adult male and female travelers for whom typhoid vaccination with Vivotif is recommended, as per standard practice.

The study will enroll 950 subjects who will be randomized at a ratio of 1:1 into two groups, A and B, of 475 subjects each. Group A will receive 6.9-10.0 x109 CFU/capsule and Group B will receive 4.0-6.8 x109 CFU/capsule, respectively.

All subjects will receive four doses of Vivotif. One dose per subject will be administered on Days 1, 3, 5 and 7.

Investigators, subjects and all personnel involved in running the study will not be aware of the actual release titer associated with the distributed lots. Blinding is maintained using the commercial packaging that does not include the actual value of the release titer.

Inclusion criteria

• Subjects are male or female aged ≥ 18 years at time of dosing
• Subjects are travelers attending travelers' vaccination clinics
• Subjects are eligible for typhoid vaccination, according to standard practice
• Subjects are expected to be able to provide follow-up information
• Subjects have an expected travel departure date more than 21 days after enrollment (to enhance follow-up by ensuring subjects remain in the US during the AE collection period)
• Subjects must sign a written informed consent

Exclusion criteria

• Subjects with a known hypersensitivity to any component of the vaccine or the enteric coated capsule
• Subjects deficient in their ability to mount a humoral or cell-mediated immune response due to either a congenital or acquired immunodeficient state including treatment with immune-suppressive or antimitotic drugs
• Subjects with an acute febrile illness
• Subjects with acute gastrointestinal (GI) illness
• Subjects who are receiving medications with antibacterial activity (including proguanil) at the time of enrollment
• Subjects with other contraindications as determined by the site investigator