HIV-positive individuals are 30- to 100-fold more vulnerable to invasive pneumococcal infections than healthy adults. Although pneumococcal vaccination may be the most effective approach to reduce the huge pneumococcal illness burden, the ideal time of immunization is still  unknown. HIV-infected individuals aged 18 years were recruited for this study and split into two age-matched groups: group 1 and group 2. Immunogenicity following vaccination with a 13-valent pneumococcal conjugate vaccine was compared using a multiplex opsonophagocytic killing test (PCV13). 67 of the 70 individuals were available for immunogenicity and safety testing. The non-inferiority criteria was not fulfilled in the post-vaccination geometric mean titer (GMT) ratios. GMTs after pneumococcal vaccination were substantially lower in group 2 compared to group 1 for all four pneumococcal serotypes examined. PCV13 was shown to be safe and well tolerated in HIV-infected individuals of all immunological statuses.

In conclusion, PCV13 immunogenicity was considerably lower in HIV-infected individuals with a CD4 T-cell count of 350 cells/L compared to those with a higher CD4 T-cell count.