The goal of this clinical trial is to learn about persistence of immunity of PCV13 in healthy population aged 2 months, 7 months-5 years. The main questions it aims to answer are the percentage of subjects reached the IgG level of ≥0.35 µg/mL, GMCs level for IgG antibody, and SAEs from one month to 12 months after the last injection.

Inclusion Criteria:

• Those who have participated in the Phase III clinical study of Beijing Minhai PCV13 and have been fully vaccinated with Minhai PCV13;
• An informed consent was required to sign by their legal guardians;
• Volunteers and their legal guardians/caregivers were able to attend the study visit as required by the protocol.

Exclusion Criteria:

• Those who had any administration history of pneumococcal polysaccharide or conjugate vaccine after participating in the Phase III clinical study;
• Prior to enrollment, patients who had a history of pneumococcal infection with one or more of the well-defined PCV13 serotypes;
• The researchers shall judge the other conditions which might be not in compliance with the requirements of this clinical trial.