Immunogenicity and Safety Study of 15-Valent Pneumococcal Conjugate Vaccine in 2-month-old and 3-month-old Healthy Volunteers

Inclusion Criteria: * Aged above 2 months (minimum to 6 weeks), term (37-42 weeks gestation) and birth weight ≥2.5 kg. * The guardian understands the vaccination and research procedures, volunteers to participate in the research and sign the informed consent. * The guardian can follow the clinical research program, will be able to follow up until 3 years after booster immunization and have the ability to use thermometers, scale and fill in diary and contact cards as required. * There was no history of other live vaccines in the past 14 days and no history of other inactivated vaccines in the seventh day. * Subaxillary body temperature \<=37.0 C. * Determine health based on medical history, physical examination, and researcher's judgment. Exclusion Criteria: * Have been vaccinated a listed or experimental pneumococcal vaccine. * History of invasive diseases caused by Streptococcus pneumoniae confirmed by bacterial culture in the past. * In the past, there was any history of vaccination or serious allergy to drugs. In the past, fever of over 39.5 C related to vaccination occurred in biological products for vaccination and prophylaxis. * History of convulsion, epilepsy, encephalopathy and psychiatry or family history. * Had abnormal labor (dystocia, device midwifery), history of asphyxia rescue and nerve organ damage. * History of pathological jaundice confirmed by diagnosis. * A history of thrombocytopenia or other coagulation disorders with definite diagnosis. * Human serum gamma globulin injection after birth. * There are known or suspected immunological abnormalities, including immunosuppressive therapy (radiotherapy, chemotherapy, corticosteroids, antimetabolites, cytotoxic drugs), HIV infection, etc. * Congenital malformations, severe malnutrition, developmental disorders, genetic defects (e.g. broad bean disease). * Severe chronic disease, infectious disease, active infection, liver disease, kidney disease, cardiovascular disease, malignant tumor. * Severe asthma. * Systemic rash, dermatophytes, skin pus or blister. * Participation in other drug clinical trials. * Anything that the researcher considers likely to affect the evaluation of the study.