The research objective is to evaluate the safety and tolerability of the inactivated rotavirus vaccine and explore its preliminary immunogenicity.

This is a Phase I, single center, randomized, double-blind, placebo-controlled, dose escalation clinical trial conducted in Hebei Province, China. The purpose of this study is to evaluate the safety and tolerability of the inactivated rotavirus vaccine and explore its preliminary immunogenicity.

Inclusion Criteria:

• Subjects aged 6-12 weeks, 1-5 years old, 18-49 years old, able to provide legal identification;
• The subjects or the legal guardians of the subject have the ability to understand the research procedure, agree to participate in the study (or the legal guardian of the subject agrees to the child's participation in the study), and signs an informed consent form;
• The subjects or their legals guardian are able to participate in all planned follow-up visits;
• On the day of enrollment, the axillary body temperature was ≤ 37.0 ℃;
• Standards for certain groups of people:

Subjects aged ≥ 1 year: Laboratory test indicators (as specified in the protocol) within the normal range, or those with abnormalities but no clinical significance (evaluated by clinical doctors); Female participants of childbearing age: non pregnant, non lactating, and agreed to take effective contraceptive measures within 8 months after participating in the study.

Exclusion Criteria:

• Previously received any rotavirus vaccine;
• Previous history of acute gastroenteritis caused by rotavirus;
• Have a history of intussusception, congenital abnormalities in the digestive system, chronic diarrhea, and other diseases in the past;
• Have any history of severe allergies to vaccines or drugs in the past, such as allergic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, and local allergic necrosis reaction (Arthurs reaction);
• Suffering from serious congenital malformations, developmental disorders, and genetic defects that may interfere with the progress or completion of the study (including but not limited to: Down syndrome, thalassemia, etc.);
• Diagnosed with congenital or acquired immunodeficiency, or suspected of having systemic diseases that may interfere with the conduct or completion of the study, such as tuberculosis, hepatitis B, hepatitis C, human immunodeficiency virus (HIV), syphilis infection, etc;
• Having a history or family history of convulsions, epilepsy, encephalopathy, and mental illness;
• Suffering from contraindications for intramuscular injection such as thrombocytopenia, any coagulation disorders, or receiving anticoagulant therapy;
• Recently receiving immunosuppressive therapy, such as systemic glucocorticoid therapy for more than 2 weeks continuously after birth or 6 months before vaccination, such as prednisone or similar drugs using >5mg/day (note: local and inhaled/nebulized steroids can be used);
• Any absence of spleen or splenectomy, functional absence of spleen caused by any circumstances;
• Hypertensive subjects (systolic blood pressure ≥ 140mmHg and/or diastolic blood pressure ≥ 90mmHg, suitable for adults);
• Three days prior to the first dose of the vaccine, there was an acute illness or a period of acute exacerbation of a chronic disease;
• Received inactivated vaccine within 7 days before enrollment and attenuated live vaccine within 14 days;
• Have received blood or blood related products or immunoglobulin (acceptable for hepatitis B immunoglobulin) within 3 months prior to enrollment;
• Plan to move before the end of the study or leave the local area for a long time during the scheduled study visit;
• The researchers believe that there are any conditions in the subjects that may interfere with the evaluation of the research objectives;
• Standards for certain groups of people:

Subjects aged 6-12 weeks: single fetus gestational age<37 weeks or>42 weeks, birth weight<2.5kg or>4.0kg; multiple fetuses; abnormal birth process (difficult labor, instrumental midwifery) or a history of asphyxia and neurological damage; children with pathological jaundice.