Objective: To evaluate whether a strategy combining a prime with a 7-valent conjugate pneumococcal vaccine (PCV) followed by a boost with the 23-valent polysaccharide vaccine (PPV) would improve immunogenicity against Streptococcus pneumoniae polysaccharides in HIV-infected patients.
Design: Randomized controlled phase II trial.
Methods: Two-hundred and twelve patients with CD4 cell counts of 200-500 cells/mul and HIV RNA< 4 log10 copies/ml, regardless of antiretroviral treatment, were randomized to receive either PCV at week 0 and PPV at week 4 (n = 106) or PPV alone at week 4 (n = 106). The proportion of responders to 0, 1-2, 3-4, 5-7 serotypes shared by the two vaccines was evaluated at week 8 and compared using a proportional odds model allowing for adjustment for CD4 cell count, HIV RNA and antiretroviral treatment.
Results: At week 8, the profile of response was better in the prime-boost group compared to the PPV group, as determined by the frequency of patients who reached both a twofold increase of serotype-specific IgG levels and IgG level >/= 1 mug/ml [proportional odds ratio (OR), 2.09; 95% confidence interval (CI), 1.25-3.51; P = 0.005]. No differences in responders were found 4 weeks after PCV or PPV alone, suggesting that PCV primed for response to PPV. Early differences between groups remained significant at week 24 (proportional OR, 2.14; 95% CI, 1.30-3.54; P = 0.003).
Conclusions: In a setting of practical care, a PCV prime-PPV boost strategy enhances the frequency, breadth and magnitude of antibody responses against SPP in HIV-infected adults.