A 5-year longitudinal follow-up study of serological responses to 23-valent pneumococcal polysaccharide vaccination among patients with HIV infection who received highly active antiretroviral therapy.

BACKGROUND: Long-term antibody responses to 23-valent pneumococcal polysaccharide vaccine (PPV) among HIV-infected patients receiving highly active antiretroviral therapy (HAART) are rarely investigated.
METHODS: Antibody responses to three pneumococcal capsular polysaccharides [Pneumococcal polysaccharide (PPS) 14, 19F and 23F] were assessed among 169 HIV-infected patients who received HAART and 23-valent PPV. Patients were stratified into four groups according to CD4 count at vaccination: group 1, CD4<100 cells/microL (n=35); group 2, CD4 100-199 cells/microL (n=36); group 3, CD4 200-349 cells/microL (n=34); and group 4, CD4>or=350 cells/microL (n=64). The proportion of patients who achieved increases in antibody titres of twofold or greater from baseline values (responders) was compared among the four groups of patients for five consecutive years after vaccination.
RESULTS: The proportion of responders to the three serotypes was significantly lower among patients in group 1 compared with those in the other three groups during yearly follow-up. Much faster loss of antibody responses was observed in group 1, although the rate of decline varied with the serotypes studied in the four groups. Compared with the nonresponders, more responders had CD4 counts >100 cells/microL at vaccination and achieved better virological suppression throughout the 5-year period, while the absolute increases of CD4 cell counts after HAART were not statistically significantly different.
CONCLUSIONS: Despite continued increases in CD4 cell counts after HAART, the proportion of HIV-infected patients who maintained antibody responses to PPV declined significantly over the 5-year follow-up period, especially among those who had CD4 counts <100 cells/microL at vaccination and who failed to achieve virological suppression.