The lack of association between aging and postvaccination levels of IgG antibody to capsular polysaccharides of Streptococcus pneumoniae

One possible explanation for the apparently reduced efficacy of pneumococcal vaccine in elderly subjects is that IgG responses to pneumococcal capsular polysaccharides (PPSs) decline with aging. We administered pneumococcal vaccine to 118 adults who ranged in age from 20 to 93 years; 33 were greater than or equal to 70 years old. Four to 6 weeks later, we measured IgG reactive with PPSs from 10 commonly infecting serotypes of Streptococcus pneumoniae. By regression analysis, a slight but nonsignificant increase in anti-PPS IgG was observed with increased age for six serotypes and a nonsignificant decrease was observed for four. Mean IgG levels and the percentage of subjects with IgG levels greater than or equal to 1 mu g/mL were no different among persons greater than or equal to 70 years of age than among those less than or equal to 69 years of age, These results show no consistent effect of aging on anti-PPS IgG levels 4-6 weeks after pneumococcal vaccination.