Efficacy, Immunogenicity and Safety of S. Flexneriza-S. Sonnei Bivalent Conjugate Vaccine in Volunteers Aged From 6 Months to 5 Years

Inclusion Criteria: * Infants and children aged from 3 months to 5 years old; * The legal representative voluntarily agrees to participate in the study and signed the informed consent form; * The legal representative voluntarily agrees to comply with the requirements of the clinical study protocol, and they can participate in all planned follow-up; * Subjects who didn't immuned with attenuated live vaccine within 14 days and inactivated vaccine within 7 days before vaccination; * Axillary temperature ≤37.0℃; * According to the medical history, physical examination and the judgment of the researcher, it is determined that the subject is in good physical condition. Exclusion Criteria: * Previous proven history of bacillary dysentery; * Subjects who are allergic to tetanus toxoid, and have any history of other vaccination or drug allergy, or a fever above 39.5 ℃ after previous vaccination; * Within 3 days before vaccination, suffering from acute diseases or in the acute episode of chronic disease or using antipyretic, analgesic and antiallergic drugs (such as acetaminophen, ibuprofen, etc.); * Had severe bowel disease, and had symptoms such as diarrhea, abdominal pain, pus and blood stool and other symptoms in the past 3 days; * With pathological jaundice confirmed by existing diagnosis; * History of thrombocytopenia or other coagulation disorders with definite diagnosis; * Known or suspected immunological deficiency (such as perianal abscess, which indicates that infants may have immune deficiency), and received long-term (≥14 days) immunosuppressive therapy (radiotherapy, chemotherapy, systemic glucocorticosteroids≥2 mg/kg/day, antimetabolic drugs and cytotoxic drugs) within half a year before vaccination, or confirmed that the parents were HIV infected; * Received immunoglobulin / blood products treatment within 3 months before vaccination; * Severe congenital malformations (functional impairment of important organs), severe malnutrition, developmental disorders and serious genetic diseases (such as severe thalassemia); * Subjects with the following diseases: 1. Serious liver and kidney diseases, cardiovascular diseases, malignant tumors and other chronic diseases; 2. Diagnosis with infectious diseases such as tuberculosis, viral hepatitis and so on; 3. Severe asthma; 4. Systemic rash, dermatophyte, skin suppuration or blister; 5. History or family history of convulsion, epilepsy, encephalopathy, mental illness; * Planning to participate or currently participating in clinical trials of other vaccines or drugs; * Any situation that the investigator believed may affect the study evaluation.