Evaluation of humoral response to heptavalent pneumococcal conjugate vaccine in HIV-infected children.

OBJECTIVE Invasive pneumococcal disease is a major cause of death in HIV-infected children. The objective of the study was to assess the quantitative antibody response to the seven pneumococcal serotypes of heptavalent pneumococcal conjugate vaccine in a group of HIV-infected children. METHODS Study comprising 40 HIV-infected children aged between 2 and 9 years followed up in a specialized outpatient clinic in São Paulo, Brazil, between 2002 and 2003. Enzyme immunoassay (ELISA) was used to measure IgG antibody titers against pneumococcus capsule. Antibodies were measured immediately before and 1 month after the second dose of the vaccine. Two response criteria were used: IgG titers >or=1.3 microg/mL in the post-immunization serology and an increase of at least 4or=-fold in post- compared to pre-immunization serology. RESULTS For the first criterion (>or=1.3 microg/mL), 26 (65%) children had serological response to the vaccine, 12 (30%) showed post-immunization IgG titers of at least 1.3 microg/mL for all seven serotypes studied. For the second criterion studied (>or=4-fold increase in post- compared to pre-immunization titers for four serotypes or more), serological response was seen in 15 (37.5%) children. CONCLUSIONS Overall response to the heptavalent pneumococcal conjugate vaccine was adequate, showing a statistically significant increase in the post-immunization geometric mean titers for the seven serotypes studied.