To compare the immunogenicity of the domestically produced PCV13 vaccine in healthy 2-month-old infants following administration via the 2+1 and 3+1 schedules, with the primary endpoint being the seroprevalence of specific IgG antibodies after completion of the vaccination series.To evaluate the safety of the 2+1 schedule in infants and young children (incidence of adverse events and serious adverse events).

Inclusion Criteria:

• 1: Age at enrollment: 2 months (60-89 days)

  2: A healthy male or female infant, born at term (≥37 weeks' gestation), with a birth weight of ≥2500 g

  3: Parents/guardians must provide written informed consent, and participants must be capable of using a thermometer and a ruler and of completing the daily log card as instructed

  4: Able to adhere to study protocols, including completing all visits and blood collections

Exclusion Criteria:

1. received any pneumococcal vaccine before enrollment or schedule to receive a non-study pneumococcal vaccine during the study
2. A history of culture-confirmed invasive disease caused by Streptococcus pneumoniae
3. Known allergy to vaccine components, including excipients, diphtheria toxoid, tetanus toxoid, etc.
4. Acute illness at enrollment or axillary temperature >37°C
5. Immune deficiency, chronic illness, or use of immunosuppressive therapy
6. Patients with thrombocytopenia, any coagulation disorder, or those receiving anticoagulant therapy
7. Participation in another clinical trial within the past 30 days or during this study
8. Has received another live attenuated vaccine within the past 14 days, or another inactivated vaccine within the past 7 days
9. Has received immunoglobulin within the past month
10. Any circumstances that researchers believe may affect the evaluation of the study