QUANTITY AND AVIDITY OF PNEUMOCOCCAL ANTIBODIES BEFORE AND UP TO 5 YEARS AFTER PNEUMOCOCCAL VACCINATION OF ELDERLY PERSONS

It is not known how long vaccine-induced type-specific pneumococcal an tibodies persist or whether age-related changes in their avidity occur ; we therefore administered pneumococcal vaccine to 15 elderly persons aged 60-67 years to determine the level and avidity of the pneumococc al antibodies before vaccination and again 4 weeks and 5 years later. Antibody levels were significantly higher after vaccination than befor e vaccination in 67% of these subjects (P < .01). On the basis of guid elines established for revaccination, we found that 60% of these elder ly persons required revaccination 5 years after primary immunization a nd that the antibody status of the remaining 40% would need to be dete rmined some years later. No significant differences in IgG antibody av idity were detected in connection with the type of pneumococcus, the v accination status of the vaccinee (i.e., whether sera were assayed bef ore vaccination or 4 weeks or 5 years later), or the age of the vaccin ee.