Immunogenicity and safety of a second administration of 13-valent pneumococcal conjugate vaccine 5 years after initial vaccination in adults 50 years and older

•Adults ≥50 years, were revaccinated with PCV13 five years after initial vaccination.•Immune responses significantly increased from before to 1 month after revaccination.•Immune responses were maintained or enhanced for most vaccine serotypes by revaccination.•The safety profile after PCV13 revaccination was acceptable.