A Multi-center, Open-labelled, Randomized, Controlled, Extended Phase Ⅲ Clinical Trial of sIPV Vaccine

Inclusion Criteria: 1\) Infants of 6 weeks old (42-47 days); 2) For whom a parent/legal guardian has given written informed consent after the study has been explained; 3) Be able to provide the vaccination records after birth; 4) Negative results in SARS-CoV-2 rapid antigen testing, within 24 hours before enrollment; 5) The participant's mother was tested negative for HIV, Syphilis, Hepatitis A, Hepatitis B infection during or before (during pregnancy) her child's enrollment to this study (the test result should be provided, and that obtained during pregnancy is acceptable). \- Exclusion Criteria: 1\) History of polio vaccination (except the OPV at birth); 2) Prior vaccination with routine infant vaccines against Diphtheria, Tetanus, Pertussis, Haemophilus influenzae type b (Hib), Pneumococcal or rotavirus; 3) History of severe allergic reaction after previous vaccinations or hypersensitivity to any vaccine component; 4) Infants with premature labor (delivery before week 37 of gestation) and low body weight (birth body weight is \<2500 g); 5) Infants with difficult labor at birth, asphyxiation rescue and history of nervous system injury; 6) Congenital malformation or development disorder, genetic defect, severe malnutrition, etc.; 7) Autoimmune disease or immunodeficiency/immunosuppression; 8) Patients with serious chronic diseases (such as Down's syndrome, diabetes, sickle cell anemia, or neurological disorders); 9) Abnormal coagulation functions (such as coagulation fac…