Subjects will be recruited and divided into 3 groups:(1)combined immunization of Sabin-IPV and DTaP, (2) Sabin-IPV only and (3) DTaP only.

After finishing the two basic vaccine EPI procedures, the immunogenicity and safety of both combined immunization group and individual vaccination groups will be compared and the data will be analyzed.

It is recommended by China Food and Drug Administration (CFDA) that studies on simultaneous immunization of Sabin-IPV and DTaP be implemented soon and the immunogenicity and safety studies should be conducted. In China according to the current vaccination schedule, the arrangement of Sabin-IPV and DTaP falls on the same date -- at infants' 3rd and 4th months of age. In order to avoid the vaccination time conflict and explore the feasibility of simultaneous immunization, we design this phase 4 clinical trial of simultaneous vaccination of the two vaccines.

To be specific, the subjects were divided into 3 groups. Group 1 : Sabin-IPV (1st, 2nd, and 3rd doses) and DTaP (1st, 2nd, and 3rd doses) are simultaneously administrated at 3,4,5 months old ; Group 2 : subjects receive 1 dose of sIPV only at 3,4,5 months old ; Group 3 : subjects receive 1 dose of DTaP only at 3,4,5 months old .

Blood samples would be collected both before vaccination and 28-40 days after the 3rd dose of vaccination. Neutralization antibody will be detected to evaluate the seroprotection rates and antibody geometric mean concentrations. The safety of both immunization schedules will be monitored too.

Inclusion Criteria:

• subjects aged 3 months old at the date of recruitment;
• with informed consent signed by parent(s) or guardians;
• parent(s) or guardians are able to attend all planned clinical appointments and
• obey and follow all study instructions;
• subjects have not been vaccinated with IPV vaccine, OPV vaccine, DTP vaccine and related vaccines;

Exclusion Criteria:

• subject who has a medical history with hypersensitiveness, eclampsia, epilepsy, cerebropathy and neurological illness;
• allergic to any ingredient of vaccine or with allergy history to any vaccine;
• subjects with immunodeficiency or suspected impairment of immunologic function (e.g. caused by HIV), or subjects are in the process of immunosuppressor therapy(Taking orally injecting of steroid hormone);
• administration of immunoglobulins within 30 days prior to this study;
• acute febrile disease(temperature ≥ 37.0°C) or infectious disease;
• have a clearly diagnosed history of thrombocytopenia or other coagulopathy,
• may cause contraindications for subcutaneous injection;
• any serious chronic illness, acute infectious diseases, or respiratory diseases;
• severe cardiovascular disease, liver and kidney diseases or diabetes mellitus with complications;
• any kind of infectious, purulent, or allergic skin diseases;
• any other factor that makes the investigator determines the subject is unsuitable for this study.