Pneumococcal conjugate vaccine administration during therapy for pediatric leukemia.

Background: Pediatric leukemia patients are at high risk of invasive pneumococcal disease. The study aim was to determine the antibody response to a 10-valent pneumococcal conjugate vaccine (PCV10) administered during chemotherapy.

Methods: An open-label study in pediatric leukemia patients: Group 1 had completed a primary 7-valent (PCV7) course and received a single PCV10 dose. Group 2 were PCV immunization naïve and received 3 doses of PCV10, administered 2 months apart. Serum samples were taken at baseline and 1 month post each PCV10 dose. Antipneumococcal serotype-specific IgG to 10 serotypes were measured by enzyme-linked immunosorbent assay and the functional response to 4 serotypes (1, 6B, 19F and 23F) was measured using opsonophagocytic assays.

Results: Thirty-nine participants were recruited between May 2010 and January 2011; group 1 (n = 27) and group 2 (n = 12). The diagnosis was acute lymphoblastic leukemia (38) and acute myeloid leukemia (1). Median age was 6.2 years (1.7-17.2 years) with 62% male. The median time from diagnosis to baseline serology was 7.4 months (1.6-36.8 months). At baseline, protective geometric mean concentration above the threshold (>0.35 μg/mL) ranged from 5.3% (serotype 4) to 71% (serotype 19F). More than 60% of participants in both groups were above threshold postimmunization for 7 of the 10 PCV serotypes. Opsonophagocytic assay correlated with enzyme-linked immunosorbent assay for 3 of the 4 serotypes and r ranged from 0.51 to 0.84. An injection-site reaction was reported in 73% (27/37).

Conclusions: It is safe to administer PCV10 vaccine during therapy for pediatric leukemia. It provided a satisfactory serum immune response for the majority of vaccine serotypes.