Introduction: Pneumococcal infection is a leading cause of illness and death in HIV-infected adults. Current United States guidelines for HIV-infected adults recommend a single dose of the 13-valent pneumococcal conjugate vaccine (PCV-13) at any CD4 count and at least 1 y after receipt of the 23-valent pneumococcal polysaccharide vaccine (PPV). PPV is known to lead to hyporesponsiveness to subsequent pneumococcal vaccines for at least 1 y Whether PCV-13 would be more immunogenic if administered later after PPV receipt or at higher CD4 counts has not been tested.
Methods: We prospectively collected serum from 96 HIV-infected adults before and after PCV-13 receipt, and measured antibody concentrations against 4 pneumococcal serotypes (3, 6A, 7F, and 19A) via indirect ELISA according to the WHO protocol. Post-booster antibody concentrations and fold-rise in antibody concentrations were compared according to time from PPV receipt and baseline CD4 count using univariate and multivariate analyses.
Results: PPV receipt >3 versus 1-3 y prior did not significantly change post-vaccination antibody concentrations, but was associated with slightly higher fold-rise in antibody concentration for the 3 tested serotypes included in PPV, though this only reached significance for serotype 7F. CD4 count was significantly associated with post-vaccination antibody concentrations for 3 of 4 serotypes, but not for fold-rise in antibody concentration for any serotype.
Conclusion: Waiting longer than 1 y after PPV receipt to administer PCV-13 may slightly improve the antibody response to serotypes included in both vaccines. While higher CD4 count at PCV-13 administration results in higher post-vaccination antibody concentrations, this is likely because higher CD4 count is also associated with higher pre-vaccination antibody concentrations.
Keywords: CD4 Count; HIV; Pneumovax; Prevnar; adults; pneumococcus; vaccine.