Efficacy of 7vPCV vaccination in pediatric alloHSC transplant recipients. (A) Serologic response rates given in percentage of patients (n = 43) either showing seroconversion or achieving a greater than 2-fold increase of prevaccination antibody level against the 7 vaccine serotypes (4, 6B, 9V, 14, 18C, 19F, and 23F) following 2 and 3 7vPCV vaccinations. Error bars indicate 95% confidence intervals (95% CI). (B) Geometric mean antibody concentrations (GMCs) for the 7 vaccine serotypes before, after 2, and after 3 7vPCV vaccinations. Increases of GMCs following 2 vaccinations (P <.001) and further rises of GMCs following the third vaccination (P <.05) are statistically significant for all serotypes as determined by 2-tailed t test. The presumed threshold of seroprotection (≥ 0.5 μmg/mL) is indicated by the horizontal line. (C) Rates of patients exhibiting protective antibody concentrations (≥ 0.5 μmg/mL) to all 7 vaccine serotypes before, after 2, and after 3 7vPCV vaccinations for the entire study cohort as well as recipients of related (n = 21) and unrelated (n = 22) hematopoietic stem cell transplants. Differences between the related and unrelated donor group were not statistically significant (Fisher exact test).