Pneumococcal polysaccharide vaccination in allogeneic hematopoietic stem cell transplantation recipients: a prospective single-center study.

Few studies have evaluated the response of allogeneic hematopoietic stem cell transplantation [allo-HSCT] recipients to pneumococcal polysaccharide vaccine-23 [PPSV23] in the modern transplant era when more elderly patients undergo allo-HSCT. We administered a single dose of PPSV23 to 30 allo-HSCT recipients and evaluated serotype-specific antibody responses using IgG measured by enzyme-linked immunosorbent assay and opsonophagocytic assay [OPA] titers in a multiplexed opsonophagocytic killing assay. The median patient age was 54 years [range, 23-68], and the interval from allo-HSCT to vaccination was 756 days [range, 389-1903]. No severe adverse effects were observed. The median positive response rates at 1 month and 1 year post-vaccination for the 7 serotypes measured by IgG were the same at 43% [range, 33-57], while those for 8 serotypes measured by OPA were 72% [range, 55-86] and 55% [range, 52-62], respectively. Peripheral blood stem cell transplantation improved vaccine response based on OPA titers at 1 month post-vaccination. During the median follow-up period of 1135 days post-vaccination, one patient developed pneumococcal bacteremia at 998 days. Our study suggests that PPSV23 vaccination in allo-HSCT recipients is safe and may result in a serological response.