A Study to Evaluate Safety and Immunogenicity of tOPV in 1 to 5 Years and at 6 Weeks of Age

This will be a single center, open study in children (aged 1 to 5 years) and vaccine-naïve infants, as follows: 50 OPV-vaccinated children aged 1 to 5 years to receive 1 dose of tOPV (Group 1); 104 vaccine-naïve infants to receive 3 doses of tOPV administered 28 days apart (Group 2)

Inclusion criteria

• Age:

Group 1- Children aged 1-5 years, previously vaccinated with ≥ 3 doses of OPV. Group 2- Infants aged 6 weeks (-7 to +14 days) with no previous polio vaccinations.

• Healthy without obvious medical conditions that preclude the subject to be in the study as established by the medical history and physical examination.
• Written informed consent obtained from 1 or 2 parents or legal guardians as per Dominican Republic regulations.

Exclusion criteria

• Previous Vaccinations:

Group 1: Previous vaccination against poliovirus outside of the national immunization schedule and any vaccine in the previous 4 weeks.

Group 2: Any vaccination against poliovirus

• Group 2: Infants with birth weight (BW) < 2,500 gm.
• Any confirmed or suspected immunosuppressive or known immunodeficient condition including human immunodeficiency virus (HIV) infection.
• Family history of congenital or hereditary immunodeficiency.
• Major congenital defects or serious uncontrolled chronic illness (neurologic, pulmonary, gastrointestinal, hepatic, renal, or endocrine).
• Known allergy to any component of the study vaccines or to any antibiotics.
• Uncontrolled coagulopathy or blood disorder contraindicating intramuscular injections.
• Administration of immunoglobulins and/or any blood products since birth or planned administration during the study period.
• Acute severe febrile illness at day of vaccination deemed by the Investigator to be a contraindication for vaccination (the child can be included at a later time if within age window and all in/exclusion criteria are met).
• Member of the subject's household (living in the same house or apartment unit) has received OPV in the last 3 months, or is scheduled to receive OPV during the study period.
• Subject who, in the opinion of the Investigator, is unlikely to comply with the protocol or is inappropriate to be included in the study for the safety or the benefit-risk ratio of the subject.