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 factor deficiency, blood coagulation disease and blood platelet disorders) or obvious bruise or blood coagulation disorders diagnosed by the doctors; 10) Those who have received immunosuppressant therapy, cytotoxic drug therapy and inhaled corticosteroid therapy (excluding the corticosteroid aerosol therapy for allergic rhinitis and surface corticosteroid therapy for acute non-complicated dermatitis); 11) The volunteer has received blood products before inoculation of the trial vaccine; 12) The volunteer has received other study drugs within 30 days before inoculation of the trial vaccine; 13) The volunteer has received live attenuated vaccines within 14 days before inoculation of the trial vaccine; 14) The volunteer has received subunit or inactivated vaccines within 7 days before inoculation of the trial vaccine; 15) Various acute diseases or acute exacerbation of chronic diseases within recent 7 days; 16) Significant acute disease or chronic infection within the previous 7 days or axillary temperature equal and more than 37.3℃ prior to vaccination in the present study; 17) The volunteer has any other factors which are unsuitable for participation in the clinical trial as judged by the investigators. \-