Optimizing Vaccine Delivery Among Pediatric Allogeneic Hematopoietic Cell Transplant Recipients: A Quality Improvement Initiative
Authors: Copacia J , Danino D , Taylor K , Sanborn P , Abu-Arja R , Ardura M I 
Published: November 2023

Abstract

Background
Pediatric allogeneic hematopoietic cell transplantation (HCT) recipients are at risk for vaccine-preventable infections (VPI). Although evidence-based guidelines recommend starting vaccination efforts between 3-6 months post-HCT, most children remain sub-optimally vaccinated and at-risk for VPI. Our prior work demonstrated that early vaccination starting at 4-6 months post HCT was safe and immunogenic. To reduce potential patient harm from vaccine-preventable infections (VPI), we created a quality improvement (QI) initiative to increase vaccination rates among eligible pediatric allo-HCT recipients, beginning early post-HCT by implementing a best practice immunization strategy at our institution.

Methods
This QI initiative applied a quasi-experimental design and multiple bundled interventions in Plan-Do-Study-Act (PDSA) cycles to implement and sustain an early immunization strategy among allogeneic HCT recipients in our ambulatory HCT clinic from November 2018-May 2022. The study aimed to increase vaccination rates in eligible patients by providing a core vaccine bundle (pneumococcal conjugate [PCV13], Haemophilus influenzae type b [Hib], inactivated polio [IPV], diphtheria, tetanus, acellular pertussis [DTaP], and hepatitis B vaccines [HBV]) beginning at 6 months [Day+168 to 180] post-HCT, allowing a 30-day grace period for clinic scheduling. The number of subjects who completed a full vaccine series (4 PCV13, 3 DTaP/HBV/IPV and Hib) within the expected time post HCT were recorded. Subjects were ineligible for early vaccination if the indication for HCT was a primary immunodeficiency, and if at screening or vaccination, subjects had relapsed primary disease, graft failure, died, received anti-CD20 therapies in the preceding 6 months and had no evidence of B cell recovery, or were receiving augmented immunosuppression (prednisone-equivalent of ≥ 2 mg/kg/day). The process measure was the proportion of patients screened for vaccine eligibility vs all eligible allo-HCT recipients at 4 months post-HCT. The outcome measure included the proportion of eligible allo-HCT recipients who received the first doses of core vaccines at 6 months (+30 days) among the total number of eligible patients dur for early vaccination. PDSA interventions included creating and implementing a standardized vaccine clinical practice guideline, stakeholder engagement and communication, pre-clinic screening at 4 months post-HCT, creation of a vaccine order set per time post-HCT, and patient-individualized vaccine decision support recommendations.

Results
Among 72 children who underwent allo-HCT, 37 (51%) were deemed eligible for early vaccination. Review of institutional baseline data revealed that only 43% of eligible allo-HCT received the core vaccines beginning at 6 mos post-HCT. After the first two PDSA cycles, the proportion of eligible patients receiving core vaccines beginning early post-HCT increased from a baseline of 43% to 62%. After implementation of a patient-individualized vaccine decision support recommendation, early immunization rates increased to 92% and were sustained for over 2 years. In total, 33 (90%) patients, predominantly males (55%) with a median age of 9 y [range 0.33-19], received core vaccines at a median of 175 days [range 168-210] post-HCT during the study period. Among children who received early vaccination post-HCT, 82% remained eligible to continue their recommended vaccine roadmap and completed the full vaccine series by the expected 14-16 months post-HCT.

Conclusions
A multidisciplinary approach applying QI methodology and individualized vaccine decision support allowed for improved and sustained early vaccination after pediatric allo-HCT and completion of vaccine series, thereby reducing potential VPI-associated patient harm.
Figure 1. Statistical Process Control Chart (p-chart) of Quality Improvement Initiative to Improve Vaccination Delivery Starting at 6 months After Pediatric Allogeneic Hematopoietic Cell Transplantation (HCT)