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Second dose of pneumococcal vaccine may not have utility in elderly populations
A second dose of the 7-valent pneumococcal conjugate vaccine or the pneumococcal polysaccharide vaccine may yield similar antibody concentrations when given to patients between the ages of 50 to 80, according to results of a recent study.
A single dose of either vaccine may retain immunogenicity in these elderly patients.
The researchers randomly assigned 599 adults aged 50 to 80 to receive either one dose of the 7-valent pneumococcal conjugate vaccine (7vPnC) or the pneumococcal polysaccharide vaccine (PPV) followed by a dose of 7vPnC or PPV six months later. Measurements for concentrations of immunoglobulin G specific for the serotypes in 7vPnC were taken before vaccination, four to six weeks after each vaccination and one year after enrollment.
Patient groups were stratified to ensure that individuals aged 50 to 59, 60 to 69 and 70 to 80 were evenly distributed.
Baseline immunoglobulin G levels were decreased by approximately 10% per 10 years of increased age. However, responses to either vaccine were not dependent on age.
A single dose of 7vPnC was superior to PPV for serotypes 4, 9V and 23F, but not for the other four serotypes studied. Single-dose PPV was superior for serotype 19F.
The geometric mean concentrations after the second dose of both vaccine were similar for all serotypes except 19F, which was higher in participants who had received PPV than in those who had received 7vPnC (geometric mean concentration, 9.9 [95% CI, 8.27-11.85] vs. 6.74 [95% CI, 5.76-7.19]).
Goldblatt D et al. Clin Infect Dis. 2009;49:1318-1325.