Poliomyelitis (Live) Vaccine Type I Type III (Human Diploid Cell), Oral( Institute of Medical Biology Chinese Academy of Medical Sciences)

To evaluate the antibody immunity persistence of type 1 + type 3 oral attenuated live polio vaccine (human diploid cells) and type 1 + type 3 polio vaccine sugar pills (human diploid cells) combined with IPV sequential immunization, and to explore the rationality of booster immunization at 48 months of age for each sequential immunization program.

Primary objective: To compare the positive conversion rate and antibody levels of polio antibodies of types I, II, and III after sequential vaccination with 2 doses of cIPV/sIPV + 1 dose of tOPV (liquid dosage form/sugar pill) and 2 doses of cIPV/sIPV + 1 dose of bOPV (liquid dosage form/sugar pill). Secondary objectives: (1) To compare the positive conversion rate and antibody levels of polio antibodies of types I, II, and III after sequential vaccination with 1 dose of cIPV/sIPV + 2 doses of tOPV (liquid dosage form/sugar pill) and 2 doses of cIPV/sIPV + 1 dose of bOPV (liquid dosage form/sugar pill). (2) To evaluate the safety of bOPV (liquid dosage form/sugar pill) vaccine.