Jb. Rubins et al., Determination of antibody responses of elderly adults to all 23 capsular polysaccharides after pneumococcal vaccination, INFEC IMMUN, 67(11), 1999, pp. 5979-5984
The 23-valent pneumococcal polysaccharide vaccine was formulated to prevent
invasive infection in the elderly and other high-risk populations from the
most prevalent Streptococcus pneumoniae serotypes. However, the immunogeni
city of all 23 vaccine polysaccharides has not been fully characterized in
elderly adults, We previously reported that whereas the majority of elderly
subjects had vigorous immune responses to selected pneumococcal vaccine po
lysaccharides, a subset of elderly individuals responded to fewer than two
of seven vaccine serotypes after immunization. To determine whether these e
lderly low responders have a general inability to respond to pneumococcal v
accine and to determine whether elderly low responders might be identified
by their responses to a few polysaccharides, we measured antibody responses
of elderly adults to all 23 vaccine polysaccharides after pneumococcal imm
unization. As a group, elderly subjects showed a significant rise after imm
unization in geometric mean antibody levels to all 23 vaccine serotypes. Ho
wever, when individual rather than group immune responses were assessed, th
e 23-valent vaccine did not appear to be uniformly immunogenic in these eld
erly subjects. Eleven elderly subjects (20%) had twofold increases in speci
fic antibody after vaccination to only 5 or fewer of the 23 vaccine polysac
charides, and they did not respond to the most prevalent serotypes causing
invasive disease. Antibody responses to serotype 9N were found to reliably
distinguish low vaccine responders from other elderly subjects. However, no
particular group of vaccine polysaccharides could be used as a marker for
adequate immune responses if only postvaccination sera were analyzed.