Following a recommendation on October 2017 meeting of the Strategic Advisory Group of Experts (SAGE) on Immunization; low- risk bOPV-using countries may adopt 2 dose fIPV schedule prior to global OPV cessation as it provides better seroconversion than 1 full dose IPV and in the post-cessation era, the 2 fIPV doses will provide sufficient (above 90%) seroconversion. Countries, which delayed the introduction of IPV or had a vaccine stock-out, should provide 1 full dose or 2 fIPV doses to all children who were missed as soon as supply becomes available. The IPV supply situation is expected to improve in 2018; all countries are expected to have access to IPV for their routine immunization programmes from the end of the first quarter of 2018.

While immunogenicity after one and two doses of IPV and fIPV has been estimated when administered to younger children ; the immunogenicity of IPV (or fIPV) when administered at 9 months of age or later is not known. We propose to conduct a study to assess the immunogenicity of one and two doses of fIPV and IPV when administered between 9-13 months of age.

Inclusion Criteria:

1. Apparently healthy children with no obvious clinical symptom of illness
2. Parents/legal guardians of participants willing to give written informed consent and willing to comply with study protocol.
3. Free of obvious health problems (congenital abnormalities, severe malnutrition, acute or chronic diarrhea, bleeding disorder etc) as established by medical history and screening evaluation including clinical examination.
4. Resident of study area.

Exclusion Criteria:

1. Participation in another clinical trial in the 4 weeks preceding the (first) trial vaccination or planned participation in another clinical trial during the present trial period.
2. A diagnosis or suspicion of congenital or acquired immunodeficiency disorder, malignancy,
3. A diagnosis or suspicion of bleeding disorder
4. Acute or persistent diarrhoea
5. History of allergy or systemic hypersensitivity to any of the vaccine components
6. Chronic illness at a stage that could interfere with trial conduct or completion.
7. Presence of significant malnutrition
8. History of any neurological disorder or history of seizure (febrile or afebrile), or encephalopathy, encephalitis, hypotonic-hyporesponsive episode.

09. Febrile illness or acute illness on the day of inclusion

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