Immune response of elderly adults to pneumococcus: variation by age, sex, and functional impairment.

The immune response of 271 elderly persons to the new 23-valent pneumococcal vaccine was studied prospectively. Sera were obtained prevaccination, at 1 month post- and 12 months postvaccination. They were analyzed by radioimmunoassay for the presence of antibody Types 1, 3, 6A, 7F, 8, and 9N. The results showed differences in antibody levels by sex of the individual (p less than .01 pre and p = .04 at 1 month post), with women having lower antibody levels than men. Women responded better to vaccination than men (p = .05), but they also lost their acquired antibodies faster (p less than .01). No age effect and no effect of level of functioning were observed within this group of elderly individuals. Participants who died had high initial levels and responded well. Major differences between the six types were noticed. Type 6A exhibited the described pattern most clearly, whereas Type 3 often behaved in an opposite pattern from the other five types. We conclude that sex differences persist even among elderly adults, that high levels of antibodies are not necessarily an indicator of good health, and that much unexplained variation between antibody types exist.