Hospitalizations for vaccine-preventable infections among pediatric hematopoietic cell transplantation recipients in the first 5 years after transplantation.

Despite recommendations for vaccination after hematopoietic cell transplantation (HCT), immunization rates remain low leaving children at high risk for vaccine preventable infections (VPIs). However, the burden from VPIs in pediatric HCT recipients is not well known. We describe the prevalence, risk factors, and outcomes of VPI-associated hospitalizations at centers participating in the Pediatric Health Information System database. Children <18 years who underwent allogeneic or autologous-HCT between 1/1/2010-31/12/2018, were identified and prevalence of overall VPI and of each infection were determined at five time-points within 5 years post-HCT. In total, 684 of 9591 pediatric HCT recipients had a VPI-associated hospitalization, most frequently in the first 6-12 months, for an overall prevalence of 7.1% (95% CI: 6.6-7.7%). Influenza, varicella, and invasive pneumococcal infections were the most frequent. Multivariable analyses identified younger age (OR = 0.96 [95% CI: 0.93-0.99]; p = 0.013), primary immune deficiency (PID) (OR = 1.78 [95% CI: 1.11-2.84]; p = 0.016), and GVHD (OR = 1.62 [95% CI: 1.05-2.48]; p = 0.028) as independent risk factors during the initial HCT-hospitalization. Children with VPI had longer duration of hospitalization (55[51] vs 36[24] days, p < 0.001), higher rates of ICU admission (42 vs 26%, p < 0.001), and mortality (11% [n = 17) vs 6% [n = 519]; p = 0.003). Continued efforts to improve vaccination early post-HCT are warranted.