- [Show abstract] [Hide abstract] ABSTRACT: The current recommendations for active immunization after stem cell transplant (SCT) include 3 doses of 7-valent pneumococcal conjugate vaccine (PCV7) from 3 months after transplant, followed by a 23-valent polysaccharide pneumococcal vaccine (PPV23). However, until now, the immune response to PPV23 after PCV7 has not been assessed after SCT. In the EBMT IDWP01 trial, 101 patients received 1 dose of PPV23 at 12 or 18 months, both after 3 doses of PCV7. The efficacy of PPV23 was assessed 1 month later and at 24 months after transplant by the pneumococcal serotype 1 and 5 antibody levels. Serotype 1 and 5 are not included in PCV7. Although the geometric mean concentrations were significantly higher 1 month after PPV23, for both antigens, the response rates (> or =0.15 microg/mL), in the range of 68-94%, were not different between groups independent of the assessment date. One PPV23 dose after 3 PCV7 doses, already known to increase the response to PCV7, also extends the serotype coverage given 12 or 18 months after transplant.
- [Show abstract] [Hide abstract] ABSTRACT: The European Group for Blood and Marrow Transplantation has recently run a prospective, randomized trial comparing an early (3 months) vs a late (9 months) immunization program after allo-SCT with three doses of the conjugate 7-valent pneumococcal vaccine. This trial has shown that the response rate assessed 1 month after the third dose of conjugate vaccine was not inferior after an early vaccination vs a late vaccination. Part of the responder cohort of these patients (n=28) were chosen to assess the functionality of the anti-pneumococcal antibodies through an opsonophagocytic assay, 1 month after the third dose of conjugate vaccine. We have assessed the relationship between IgG titers measured by the pneumococcal ELISA and functional titers measured by opsonophagocytic assay of anti-pneumococcal antibodies. We found a significant correlation between titers for both assays, and conclude that the response to PCV7 after SCT induces functional antibodies.