Diphtheria, Tetanus, Pertussis, and Poliovirus Vaccine Trial in Young Children

Inclusion Criteria:

* Age Requirement: volunteers aged 4-6 years, 18-24 months, and 2 months.
* History of preventive inoculation: (1)children aged 4-6 years who have completed immunization with 4 doses of DTP vaccine or another combination vaccine containing DTP antigen components in accordance with the National Immunization Program, and who have not yet received the fifth dose of DTP vaccine; (2)children aged 18-24 months have completed basic immunization with DTP vaccine or another combination vaccine containing DTP antigen components (3 doses) and basic immunization with poliovirus vaccine (3 doses) in accordance with the National Immunization Program, and have not yet received a booster dose of DTP vaccine (the 4th dose) or a booster dose of poliovirus vaccine (the 4th dose); (3) infants aged 2 months have not yet received vaccines containing DTP antigen components, vaccines containing poliovirus antigen components, 13-valent pneumococcal polysaccharide conjugate vaccine, haemophilus influenzae type b conjugate vaccine, or group A and C meningococcal and haemophilustype b conjugate vaccine.
* Provision of Legal Identification: participants and their legal guardians or appointed representatives must provide valid legal identification documents.
* Informed Consent: participants, legal guardians, or appointed representatives of volunteers must have the capacity to understand the informed consent document and the research process, voluntarily participate, sign the informed consent form, and be able to comply with the requirements in the study as well as complete relevant visits on time.
* 2 months old: full term infant (37 weeks ≤ gestational age \< 42 weeks) with a birth weight ≥ 2500 g.

Exclusion Criteria:

* axillary temperature \> 37.3℃.
* History of pertussis, tetanus, diphtheria, or poliomyelitis.
* History of abnormal labor and delivery at birth (dystocia or instrumental delivery), asphyxia, or neurological impairment, or history of clinically diagnosed pathological jaundice (applicable only to participants aged 2 months or 18-24 months).
* Allergy to any component of the investigational vaccine (such as aluminum hydroxide), or a history of severe allergic reactions to any vaccine or drug, or other serious adverse reactions, such as anaphylactic shock, generalized diffuse mucocutaneous angioedema, laryngeal obstruction caused by angioedema, or other life-threatening adverse reactions.
* Receipt of any inactivated vaccine or subunit vaccine within 7 days before administration of the investigational vaccine, or any live attenuated vaccine within 14 days before administration of the investigational vaccine.
* Acute diseases (such as fever) or acute exacerbations of chronic diseases within 3 days before receipt of the first dose of the investigational vaccine.
* Use of antipyretic analgesic, anti-allergic, or antiviral drugs within 3 days before receipt of the first dose of the investigational vaccine.
* History of seizures, epilepsy, encephalopathy, or psychiatric disorders, or a family history of any of the above conditions.
* Severe congenital malformations, developmental disorders, or congenital diseases , or other clinically diagnosed severe chronic diseases, including but not limited to severe diseases of the neurological, cardiovascular, hematological and lymphatic, immune, renal, hepatic, gastrointestinal, respiratory, metabolic, and skeletal systems, or a history of malignant tumors.
* Contraindications to intramuscular injection or venipuncture, such as hereditary bleeding tendency or coagulation disorders, history of bleeding disorders, or diagnosed thrombocytopenia.
* Infectious diseases that may interfere with the conduct of the trial.
* Surgical splenectomy for any reason, splenic dysfunction, or asplenia due to any cause, or resection or partial resection of other vital organs.
* Blood loss (≥400 mL), receipt of a blood transfusion, or use of blood products within 3 months before receiving the first dose of the investigational vaccine.
* Receipt of immunosuppressive therapy within 6 months before receiving the first dose of the investigational vaccine.
* Participation in or plan to participate in any clinical trial.
* Laboratory test results are abnormal and have clinical significance in 18 months to 6 years.
* Unsuitable for participation in the trial, as judged by the investigator.