The study will compare the transmissible levels of poliovirus type-2 detected in stool samples collected at the time of the nOPV2 challenge and subsequent timepoints in 3 groups of newborns receiving an nOPV2 dose at birth and primed with 3 doses of IPV (6 - 10 - 14 weeks of age).

To meet the urgent public health need regarding cVDPV2 outbreaks, a novel type 2 OPV (nOPV2) vaccine was developed using attenuated serotype 2 polioviruses derived from a modified Sabin 2 infectious cDNA clone generated by modifying the Sabin-2 ribonucleic acid (RNA) sequence to improve genetic stability and make the strains less prone to reversion to virulence. Clinical trials in adults, children, and infants demonstrated that nOPV2 vaccine is safe, well tolerated, and immunogenic. These include a phase 2 study of vaccine-naïve neonates in Bangladesh who received either two doses of nOPV2 or two doses of placebo at birth and 4 weeks of age concluded that the vaccine was well tolerated and immunogenic, as 90% of the infants seroconverted at 2 weeks post second dose. Overall 99% of infants had protective levels of neutralizing antibody at this time in contrast to the seroprotection rate of 56% in the placebo group.

Although immunogenic, the effect of nOPV2 on virus transmission is still unclear. This phase 3 study aims to compare the transmissible levels of poliovirus type-2 detected in stool samples collected at the time of the nOPV2 challenge (pre-challenge) and subsequent timepoints in 3 groups of newborns receiving an nOPV2 dose at birth and primed with 3 doses of IPV (6 - 10 - 14 weeks of age).

Inclusion Criteria:

1. Newborn infants of maximum 1 week of age with birth weight > 2,500 g.
2. Healthy infants without obvious medical conditions like immunodeficiency diseases, severe congenital malformations, severe neurological diseases or any other disease that require high doses of corticosteroids or immunotherapies that preclude the subject from participating in the study as established by medical history and physical examination.
3. Written informed consent obtained from both parents or legal guardian(s) as per country regulations.
4. Resides in the area and parents willing to adhere to all study procedures.

Exclusion Criteria:

1. Any confirmed or suspected immunosuppressive or known immunodeficient condition including human immunodeficiency virus infection in the potential participant or any member of the participant's household.
2. Household member who has receive any novel OPV 1 month before birth of this study's participant up through 1 month post-last-dose.
3. Family history of congenital or hereditary immunodeficiency.
4. Major congenital defects or serious uncontrolled chronic illness (neurologic, pulmonary, gastrointestinal, hepatic, renal, or endocrine).
5. Known allergy to any component of the study vaccines or to any antibiotics that share molecular composition with a component of the study vaccines.
6. Uncontrolled coagulopathy or blood disorder contraindicating intramuscular injections (of IPV)
7. Administration of immunoglobulins and/or any blood products since birth or planned administration during the study period.
8. Acute severe febrile illness (≥37.5 °C) on the 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 inclusion criteria are met.).
9. Participant 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 participant.
10. Infants from multiple births or born prematurely (< 37 weeks of gestation).