A Phase 2 Study to Evaluate the Safety and Immunogenicity of Two Oral Poliovirus Vaccine Candidates

Inclusion Criteria

• For Groups 1, 2, 3 and 4: healthy males or females, from 18 to 50 years of age inclusive, having previously received at least 3 doses of OPV more than 12 months before the start of the study;
• For Groups 5, 6 and 7: healthy males or females, from 18 to 50 years of age inclusive, having previously received at least 3 doses of IPV more than 12 months before the start of the study;
• Having residence in Belgium;
• In good physical and mental health as determined on the basis of medical history and general physical examination performed at Day 0;
• Female subjects of childbearing potential must agree to the use of an effective method of birth control throughout the study and up to 3 months after last vaccine dose;
• Willing to adhere to the prohibitions and restrictions specified in this protocol;
• Informed Consent Form (ICF) and Code of Conduct signed voluntarily by the subject before any study-related procedure is performed, indicating that the subject understands the purpose of any procedures required for the study and is willing to participate in the study.

Exclusion Criteria

• A condition that, in the opinion of the Investigator, could compromise the well-being of the subject or course of the study, or prevent the subject from meeting or performing any study requirements;
• For Groups 5, 6 and 7: ever having received any OPV in the past;
• Any travel to polio endemic countries or countries with evidence of recent (within last 6 months) wild or vaccine-derived poliovirus circulation during the total duration of the study;
• Professional handling of food, catering or food production activities during the total duration of the study;
• Having Crohn's disease or ulcerative colitis or having had major surgery of the gastrointestinal tract involving significant loss or resection of the bowel;
• A known allergy, hypersensitivity, or intolerance to the study vaccine or the placebo, or to any of their components or to any antibiotics;
• Any confirmed or suspected immunosuppressive or immunodeficiency condition (including human immunodeficiency virus [HIV] infection, hepatitis B or C infections or total serum immunoglobulin A [IgA] level below laboratory lower limit of normal [LLN]);
• Will have household or professional contact with known immunosuppressed people or people without full polio vaccination (i.e. complete primary infant immunization series), e.g. babysitting during the total duration of the study;
• Neonatal nurses or others having professional contact with children under 6 months of age during the total duration of the study;
• Chronic administration (i.e., longer than 14 days) of immunosuppressant drugs or other immune-modifying drugs within 6 months prior to the first vaccine dose or planned use during the study. For instance, for corticosteroids, this means prednisone, or equivalent, ≥ 0.5 mg/kg/day (inhaled and topical steroids are allowed whereas intra-articular and epidural injection/administration of steroids are not allowed);
• Presence of contraindications to administration of the study vaccine on Day 0: acute severe febrile illness deemed by the Investigator to be a contraindication for vaccination or persistent diarrhea or vomiting;
• Indications of drug abuse or excessive use of alcohol at Day 0 (males: > 21 units/week; females > 14 units/week);
• Being pregnant or breastfeeding. Women of childbearing potential will undergo a urine pregnancy test at each vaccination visit. Subjects with a positive pregnancy test will be excluded;
• Participation in another clinical study within 28 days prior to entry in this study or receipt of any investigational product (drug or vaccine) other than the study vaccine within 28 days prior to the first administration of study vaccine, or planned use during the study period;
• Administration of any vaccine other than the study vaccine within 28 days prior to the first dose of study vaccine and during the entire study period