A randomized controlled trial was conducted in China in 2015. After informed consent was obtained from a parent or legally acceptable representative, healthy newborn babies were randomly allocated to one of six groups: cIPV-bOPV-bOPV, cIPV-tOPV-tOPV, cIPV-cIPV-bOPV, cIPV-cIPV-tOPV, cIPV-cIPV-cIPV, and tOPV-tOPV-tOPV. The key eligibility criteria were: full-term birth (37-42 weeks of gestation), birthweight ≥2·5 kg, no obvious medical disorders and no polio vaccination. Infants received following three doses sequentially with 4- 6 weeks interval after collecting blood sample: cIPV-bOPV-bOPV, cIPV-tOPV-tOPV, cIPV-cIPV-bOPV, cIPV-cIPV-tOPV, cIPV-cIPV-cIPV, and tOPV-tOPV-tOPV; and will be proactively followed up for observing adverse events after the first dose and 30 days after all doses. Antibodies of type 1, 2, and 3 poliovirus were tested 30 days after the third dose. The primary study objective was to investigate immunogenicity and safety profile of different vaccine schedules, evaluated by seroconversion, seroprotection and antibody titre against poliovirus types 1, 2, and 3 in the per-protocol population.