Clinical Trial of the 24-valent Pneumococcal Polysaccharide Conjugate Vaccine (CRM197/Tetanus Toxoid)

This clinical trial consists of Phase I and Phase II. The objective is to evaluate the safety and immunogenicity of the 24-valent pneumococcal polysaccharide conjugate vaccine (CRM197/tetanus toxoid) in individuals aged 2 months (minimum 6 weeks) and older.

Inclusion Criteria: Phase I: * Individuals aged 2 months (minimum 6 weeks), 7 months to 5 years, and 18 years and older who are willing to provide identification * The trial participant and/or guardian (legal representative) has voluntarily signed the informed consent form after providing informed consent * Children aged 5 and under who have not previously received a pneumococcal vaccine * People aged 18 and older who have not received a pneumonia vaccine in the past five years Phase II (age ≥50 group): * People aged 50 and older who are willing to provide identification documents * The trial participants voluntarily signed the informed consent form after providing their informed consent * People aged 50 and older who have not received a pneumonia vaccine in the past five years Phase II (2-month-old group (minimum 6 weeks)): * Individuals aged 2 months or older (minimum 6 weeks) who are willing to provide identification documents * The guardian (authorized representative) of the trial participant has voluntarily signed the informed consent form after providing informed consent. * Infants aged 2 months (minimum 6 weeks) who have not previously received a pneumococcal vaccine Exclusion Criteria: * Exclusion criteria for the first dose: * Preterm birth (delivery before 37 weeks of gestation), low birth weight (\2 mg/kg/day or ≥20 mg/day of prednisone or prednisone-equivalent dose) (excluding topical corticosteroids such as inhaled, nasal spray, intra-articular, eye drops, or ointments; topical use must not exceed the dose recommended in the product label or result in any signs of systemic exposure). Individuals who have used long-acting immunomodulatory drugs (e.g., infliximab) within 6 months prior to the first dose or who plan to use such drugs during the trial (applicable to the Phase II group aged ≥50 years and the Phase I group aged 7 months and older) * Received blood products (excluding hepatitis B immunoglobulin) within 3 months prior to receiving the investigational drug * Participation in any other clinical trial involving a drug or vaccine within the 6 months prior to enrollment, or currently participating in such a trial, or plans to participate in such a trial during the study period * Received an injectable live attenuated vaccine within 14 days prior to receiving the investigational drug, or received any other vaccine within 7 days * Underarm temperature of 37.3°C or higher prior to vaccination * According to the researchers' assessment, the trial participants had other factors that made them unsuitable for participation in the clinical trial Exclusion criteria for the 2nd, 3rd, and 4th doses: * Individuals who experienced a severe allergic reaction following the previous dose of the vaccine * Individuals who experienced a serious adverse reaction causally related to a previous dose of the vaccine * Other potential causes ruled out by the researchers