The Immunogenicity of 7‐Valent Pneumococcal Conjugate Vaccine versus 23‐Valent Polysaccharide Vaccine in Adults Aged 50–80 Years

Abstract

Background.Infections with pneumococci are a major cause of morbidity and mortality in the elderly population. Although 23-valent pneumococcal polysaccharide vaccine (PPV) is recommended for elderly persons, the potential benefits of conjugate vaccine use in this age group remain unclear. Methods.We performed an open-label, randomized study that compared 7-valent pneumococcal conjugate vaccine (7vPnC) with PPV in 599 adults aged 50–80 years. Vaccinees received either 1 dose of 7vPnC or PPV or 1 dose of 7vPnC followed by a dose of 7vPnC or PPV 6 months later. Groups were stratified so they contained similar numbers of individuals aged 50–59, 60–69, and 70–80 years. Concentrations of immunoglobulin G specific for the serotypes in 7vPnC were measured before and 4–6 weeks after each vaccination and 1 year after enrollment. Results.Although baseline antibody levels were slightly lower in the older age groups, responses (fold rises) to either vaccine did not depend on age. Single-dose 7vPnC was superior for only 3 serotypes. Administration of a second dose of PPV or 7vPnC was similarly immunogenic in adults primed with 7vPnC, and titers after a second dose were similar to the first. Conclusions.Pneumococcal vaccines retain their immunogenicity when administered into the eighth decade of life, but a second dose, when assessed by antibody titers alone, has little utility. 7vPnC vaccines do not lead to subsequent hyporesponsiveness. Clinical trials registration. http://www.clinicaltrials.gov/NCT00197821.