Long-term antibody persistence study (3 years after last dose) of the 7-valent pneumococcal conjugate vaccine in young children in China.

•In a previous study, Chinese infants were vaccinated with PCV7, PCV7+DTaP, or DTaP.•Antibody persistence was assessed at a single time point 3years after last dose.•After 3years, serum IgG had declined but remained higher than before vaccination.•PCV7 serospecific antibodies were generally similar after PCV7 and PCV7+DTaP.•Protective immunity was not influenced by the concomitant administration of DTaP.