Kinetics of antibody concentration and avidity for the assessment of immune response to pneumococcal vaccine among children with bone marrow transplants

The kinetics of the immune response to the 23-valent pneumococcal polysacch aride vaccine (PPV) were studied in 38 children who received bone marrow tr ansplants (BMTs), Antipneumococcal antibody concentrations increased 1 and 3 months after vaccination for all 5 serotypes tested, but, in 21 children, the vaccine was not adequately immunogenic, Children vaccinated <18 months after receiving a BMT had a 4.2-fold increased odds of poor response (P =. 06). Antibody concentrations returned close to baseline levels 9 months aft er vaccination. Avidity declined significantly as early as 1 month after va ccination and remained low thereafter. Antibody concentration responses to PPV were superior among 9 healthy control children (P =.001); 37 of 38 chil dren with a BMT elicited adequate, persistent immune responses to Haemophil us influenzae conjugate vaccine. Immune responses to PPV in children with a BMT are suboptimal, short lived, and associated with declining avidity. Th e different kinetics of antibody concentration and avidity indicate that bo th markers should be used for evaluating pneumococcal vaccines in this high -risk population.