Widespread use of the 13-valent pneumococcal conjugate vaccine (PCV13) in infants and the associated indirect protection in adults has highlighted the significant burden of pneumococcal disease caused by serotypes unique to 23-valent pneumococcal polysaccharide vaccine (PPSV23) in older adults.
This study evaluated the safety and immunogenicity of sequential administration of PCV13 followed by PPSV23 either 8 weeks (Group#1) or 26 weeks (Group#2) later in adults ≥50 years old. Serotype-specific opsonophagocytic activity (OPA) geometric mean titers (GMTs) were measured prior and 30 days postvaccination.
Proportions of participants reporting any AE were comparable between both groups. More participants in Group#1 (81.9%) reported injection site AEs following PPSV23 than Group#2 (64.0%). At Week 12, OPA GMTs to 12 shared serotypes between PPSV23 and PCV13 in Group#1 were noninferior to Group#2; OPA GMTs to 6 serotypes unique to PPSV23 were superior in Group#1 than Group#2. Overall, OPA GMTs for all tested serotypes were comparable by Week 30, after both groups had received PCV13 and PPSV23.
Sequential administration of PCV13 followed by PPSV23 at 2-month or 6-month intervals was generally well-tolerated. Serotype-specific OPA GMTs were comparable, regardless of dosing interval. Administration of PPSV23 did not hinder immune responses induced by PCV13.