All babies who visit study institution for routine vaccination at 6 weeks of age and immunized with birth dose of bOPV will be considered for the enrolment. If a baby fulfils the eligibility criteria, a complete informed consent process will be followed as per the applicable regulatory requirements. As IPV for the study is already licenced and being given to millions of infants in India as per the present routine immunization schedule, it is not proposed to audio-video record the informed consent process

Babies fulfilling eligibility criteria and whose parents have provided informed consent will be randomized into one of the four study arms (A, B1, B2 & C). On enrolment at week six, one millilitre (ml) of blood sample will be collected from each study participant by venepuncture followed by administration of vaccine/s as per the allocated study arm. Parents will be advised to avoid any other vaccine from centres other than the study site. For every study infant, a study specific immunization card will be issued indicating the baby to be a study subject and that all routine vaccinations will be advised and taken care of by the study site investigator during this period. Parents will be informed about the date of next follow visit during the previous visit. Reminder telephone contacts/household visits will be arranged through study staff.

At 10 and 14 week visits, the study vaccine/s will be administered as per the allocated study arm. At 14 week visit one ml blood will be collected from each study participant by venepuncture followed by administration of vaccine/s as per the study arm. At 18 weeks, one ml blood will be collected by venepuncture in all the study arms.

In study arm A, IPV full dose will be given intramuscularly in the anterolateral side of the right thigh using AD syringe. In arm B1 and C, fractional dose IPV will be administered intradermally in right upper arm using BCG needle syringe. In Arm B2, fractional dose IPV will be administered intradermally in right upper arm using West/Helm adapter intradermal device.

The study subjects will continue getting other EPI vaccines concurrently, except polio vaccines which they shall receive as per the study arm. After having fulfilled the study requirements at 18 weeks, infants will exit the study. The infants will be referred to the routine vaccination program for the subsequent vaccination according to the national immunization schedule.

All trial related interventions will be conducted by study personnel; the only subject compliance required is to abide by scheduled visits and fill subject diary cards.