This is a phase III assessing the safety and immunogenicity of adjuvanted the reduced dose inactivated polio vaccine, IPV-Al SSI given as a booster vaccination to infants who were previously immunised with primary vaccination of IPV-Al SSI or IPV SSI in the VIPV-07 trial at age 2, 4, and 6 months. The IPV-Al SSI vaccine will be given at the age of 15-18 months.

At Visit 1 (screening, blood sample, and vaccination), the subject's eligibility is assessed according to the pre-specified in-/exclusion criteria. Information on medical history, and concomitant medication are collected and a physical examination is performed and vital signs are measured (demographics data is captured from the VIPV-07 database). The health assessment of the subject will include measurement of height, weight, temperature, heart rate, respiratory rate (breathing) and a general physical examination (which can include skin, head, eyes, ears, nose, throat, heart, lungs, lymph nodes, abdomen, and the musculoskeletal system). A pre-vaccination blood sample is taken for polio antibody determinations. The subject is vaccinated with IPV-Al (and concomitant vaccine(s) according to national guidelines, if relevant) and subsequently observed for immediate adverse events 30 minutes after the vaccination. An eDiary, a thermometer and a ruler are handed out to the parent(s)/guardian(s) for measurements and recording of temperature, injection site reactions and solicited systemic adverse events (AEs). These activities are performed daily, starting on the day of the vaccination and the following 2 days and until resolved. Any other AEs are recorded in the eDiary as instructed by the trial staff. A contact to the parent(s)/guardian(s) via telephone will be made after the vaccination visit to remind and check if the parent(s)/guardian(s) have any questions regarding how to fill in the eDiary.

At Visit 2 (blood sample and trial completion), 1 month after Visit 1, the eDiary is collected, adverse events and concomitant medications are recorded, a blood sample for poliovirus antibody determination is taken and the end of the trial page is completed.

In addition to the trial vaccine, the trial subjects will receive concomitant routine childhood vaccinations. The trial vaccine is administered in the anterolateral aspect of the right thigh, whereas the other injectable childhood vaccines are administered in the left thigh.

Inclusion Criteria:

1. Infants having completed the VIPV-07 trial
2. Healthy assessed from medical history and physical examination
3. Parent(s)/guardian(s), according to the local legal requirements, have been properly informed about the trial and have signed the informed consent form
4. Parent(s)/guardian(s), according to the local legal requirements, have granted access to the infant's trial related medical records
5. Parent(s)/guardian(s), according to the local legal requirements, are likely to comply with trial procedures

Exclusion Criteria:

1. Previously vaccinated with OPV
2. Previously vaccinated with IPV outside the VIPV-07 trial
3. Known or suspected immunodeficiency (e.g. leukaemia or lymphoma) or family history of congenital or hereditary immunodeficiency. HIV infection is not an exclusion criterion
4. Severe uncontrolled chronic disease (e.g. neurologic, pulmonary, gastrointestinal, hepatic, renal or endocrine)
5. Known or suspected allergy to vaccine constituents (e.g. hypersensitivity to formaldehyde, aluminium or 2-phenoxyethanol)
6. Previous Yellow Fever vaccination
7. Uncontrolled coagulopathy or blood disorder contraindicating intramuscular injections or blood sampling
8. In treatment with systemic corticosteroids given p.o., i.v., i.m. ≤ 1 month prior to inclusion or during the trial. Subjects administered corticosteroid topically or by asthma inhalators are eligible for inclusion
9. Treatment with a product, which is likely to modify the immune response (e.g blood products and immunoglobulins) ≤ 3 months prior to inclusion or planned during the trial period
10. Participating in another interventional clinical trial
11. Not suitable for inclusion in the opinion of the investigator

EudraCT