Phase II Clinical Trial of 24-valent Pneumococcal Polysaccharide Conjugate Vaccine

Inclusion Criteria: 1. Volunteers aged 18 and above on the day of screening, and can provide legal identification; 2. Informed consent must be obtained from the volunteer and signed informed consent form; 3. Volunteers are able and willing to comply with the requirements of the clinical trial protocol and can attend all visits; 4. Armpit body temperature ≤ 37.0 °C on the day of enrollment. Exclusion Criteria: 5. Previous vaccination with pneumococcal conjugate vaccine, prior vaccination with pneumococcal polysaccharide vaccine for less than 3 years, or previous history of invasive disease caused by Streptococcus pneumoniae; 6. Have any history of severe allergies in the past, such as anaphylactic shock, allergic laryngeal edema, Henoch-Schonlein purpura, thrombocytopenic purpura, local allergic necrosis reaction (Athus reaction), etc.; 7. Have been diagnosed with congenital or acquired immunodeficiency, or have recently received immunosuppressant therapy, such as systemic glucocorticoid therapy such as prednisone or similar drugs \>5 mg/day for more than 2 consecutive weeks in 1 month prior to vaccination); 8. Suffering from more serious cardiovascular diseases, such as arrhythmia, conduction block, myocardial infarction, severe hypertension that cannot be controlled by medication (systolic blood pressure ≥ 160 mmHg or diastolic blood pressure ≥100 mmHg when measured on site); 9. Those who have acute febrile illness or acute infectious disease or have cold symptoms, advanced influenza and take medication; 10. History of nervous system damage, severe congenital malformations, severe developmental disorders, severe genetic defects, severe malnutrition, etc.; 11. Have a history or family history of epilepsy, encephalopathy, or psychiatric disorders; 12. Those who have been diagnosed with thrombocytopenia, any abnormal coagulation function (such as coagulation factor deficiency, coagulation disorders, platelet abnormalities, etc.) or contraindications to intramuscular injection such as anticoagulant therapy; 13. asplenia, functional asplenia, and asplenia or splenectomy due to any cause; 14. Suffering from severe chronic diseases or the disease is in the advanced stage and cannot be controlled smoothly; 15. Have received blood or blood-related products or immunoglobulins within 3 months; 16. Received live attenuated vaccine within 14 days; 17. Other vaccinations within 7 days; 18. Received other investigational drugs or vaccines within 1 month; 19. Is participating in or plans to participate in clinical studies of other drugs or vaccines during the study period; 20. Any other condition that, in the opinion of the investigator, may interfere with the study evaluation; 21. Exclusion Criteria for Partial Populations: Females of childbearing potential (18\~49 years old): positive urine pregnancy test on the day of enrollment, lactation, or pregnancy plans within 6 months.