Safety and immunogenicity of 15-valent pneumococcal conjugate vaccine in pneumococcal vaccine-naive adults >= 50 years of age

Background: Pneumococcal disease remains a public health priority in adults. Safety and immunogenicity of 15-valent pneumococcal conjugate vaccine (PCV15) containing 13 serotypes included in 13-valent pneumococcal conjugate vaccine (PCV13) plus 2 additional serotypes (22F and 33F) was evaluated in adults >= 50 years old (NCT01513551). Methods: 691 adults received one dose of PCV15, PCV13, or 23-valent pneumococcal polysaccharide vaccine (PPV23) and were followed 14 days for safety. Serotype-specific IgG geometric mean concentrations (GMCs) and opsonophagocytic activity (OPA) geometric mean titers (GMTs) were measured immediately prior and 1-month postvaccination. Results: Safety profiles were comparable across vaccination groups. PCV15 induced comparable levels of IgG GMCs and OPA GMTs to PCV13 and PPV23 for shared serotypes. Serotype-specific antibodies were numerically higher among recipients of PCV15 than PCV13 and PPV23 for 7 and 12 shared serotypes, respectively; and lower for 4 and 1 serotype(s), respectively. PCV15 induced higher IgG and OPA antibodies than PCV13 or PPV23 for serotypes unique to PCV15 (22F and 33F not in PCV13; 6A not in PPV23). Conclusions: PCV15 displayed an acceptable safety profile and induced IgG and OPA to all 15 serotypes included in the vaccine, at levels comparable to PCV13 and PPV23 for shared serotypes with these vaccines. Study identification: V114-002. (C) 2018 Merck & Co., Inc. (C) 2017 Elsevier Ltd. All rights reserved.