Immunogenicity of After Primary Immunization and Booster Immunization of sIPV

Inclusion Criteria: * Participated in the previous study (ID: PRO-sIPV-MA4001-JX) * Subjects in the Primay immunization group(aged 2-3 months) need to complete 3 doses of sIPV vaccination, and the simultaneous vaccination group DTaP needs to complete 3 doses of vaccination; the booster immunity group(aged more than 18 months) needs to complete sIPV vaccination, and the simultaneous vaccination group needs to complete the corresponding vaccination; * There should be an interval of 1-9 months between the last dose of vaccination and the date of blood sample collection; * The guardian of subjects need to agree to sign the informed consent form. Exclusion Criteria: * The interval between vaccination and blood collection is less than 1 month, or more than 9 months; * Subjects were participating in other clinical studies of vaccines or drugs; * Other conditions that make subjects unsuitable for participating in this study judged by investigator's