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 .
