Clinical Study on Lot-to-lot Consistency and Immune Persistence of Three Commercial Batches of PPSV23

Inclusion Criteria: * Healthy volunteers aged 18-59; * Voluntarily participate and sign an informed consent form; * Subjects are able to comply with the requirements of the clinical study protocol and complete the prescribed follow-up; * Has not received pneumococcal vaccine or any other preventive products recently (has not received attenuated live vaccine within 14 days, has not received inactivated vaccine within 7 days); * Underarm temperature ≤ 37.0 ℃; * Female participants of childbearing age agree to take effective contraceptive measures within 3 months from the start of the study until the full vaccination period. Exclusion Criteria: * Subjects with a history or family history of progressive neurological disorders such as epilepsy, encephalopathy, and mental illness; * Has a history of severe allergies to any drugs or vaccines in the past; * Has a allergy history to any component of the experimental vaccine (the main components of the vaccine include type 23 pneumococcal polysaccharides, sodium chloride, sodium dihydrogen phosphate, and sodium dihydrogen phosphate); * Suffering from severe cardiovascular diseases (heart disease, pulmonary heart disease, pulmonary edema, drug-resistant hypertension (systolic blood pressure ≥ 160mmHg and/or diastolic blood pressure ≥ 100mmHg)); drug-resistant diabetes; * Subjects with a history of thrombocytopenia or other coagulation disorders that may cause contraindications for subcutaneous injection; * Subjects with known immunological dysfunction or low levels, or HIV infection; * Any situation leading to splenomegaly, splenectomy, or functional splenomegaly; * Malignant tumors, active or treated tumors that have not been clearly cured, or are likely to recur during the study period; * Anti tuberculosis prevention or treatment is under way; * Subjects who are participating in or planning to participate in clinical trials of other drugs or vaccine clinical trials throughout the entire observation period; * Women of childbearing age are in pregnancy (positive urine pregnancy test) or lactation period; * Any situation that the researcher believes may affect the evaluation of the study.