Health promotion after hematopoietic cell transplant: Barriers to survivor revaccination.
Authors: Wickline Mihkai , Carpenter Paul , Iribarren Sarah , Reding Kerryn , Berry Donna Lynn 
Published: September 2024

358

Background:
Comprehensive hematopoietic cell transplant (HCT) survivorship care includes revaccination (RV) to restore immunity to vaccine preventable diseases (VPDs). No published studies have reported the barriers or facilitators to complete RV. Since HCT survivors are at higher risk for infectious morbidity and mortality, it is imperative to understand RV complexity to better inform health promotion measures.
Methods:
A mixed methods, cross-sectional approach was selected to study US adults surviving 2-8 years post-HCT at a major transplant center using a de novo survey. Prevalence of vaccine confidence (VC) levels were determined with descriptive statistics. Relationships were explored between VC and RV outcomes (or intentions) using Fisher’s exact test and between VC and predictors using logistic regression. Open-ended VC responses about constructs (benefits, trust, harms) were analyzed using inductive thematic analysis. Prevalence of other barriers/facilitators were determined, along with their association with RV outcomes using logistic regression and relationships between most frequent barriers (or facilitators) and RV outcomes using Fisher’s exact test. Open-ended barrier/facilitator responses were analyzed using deductive content analysis and the
WHO behavioral and social drivers of vaccination framework.
Results:
Of 332 participants, 69% reported high, 20% medium, and 11% low VC. RV intent (p<.001) and outcomes (p=.04) correlated with VC. Multiple factors were associated with high VC. Merged analysis created a narrative about the relative importance of VC constructs: the low VC group relayed (dis)trust>harms>benefits, the medium VC group relayed trust>benefits~harm, and the high VC group relayed benefits>trust>harm. Among five most-reported RV barriers, two (on immunosuppression [p=.001], insufficient immune recovery [p<.001]) were associated with no or partial RV. Among five most-reported RV facilitators, three (having a clear vaccine calendar [p=.032], being able to contact HCT center about vaccine question [p=.018], getting vaccines at HCT center [p=.04]) were associated with complete RV. With each additional reported barrier, the odds of being completely revaccinated were lower (OR 0.58; 95% CI 0.46-0.72, p<.001), and with each additional reported facilitator, the odds of being completely revaccinated were higher (OR 1.31; 95% CI 1.05-1.63, p<.001). Content analysis suggested that most barriers were practical issues (e.g. clear calendar of which vaccines when, insurance coverage). Overall, barriers outweighed facilitators in the no and partial RV groups whereas facilitators outweighed barriers in the complete RV group.
Conclusions:
Only 69% of survivors had high VC which significantly affected RV intent and outcome, as did practical barriers and facilitators.These findings expand our knowledge about factors influencing RV in US HCT survivors and could inform future RV standards, policies, and research on testing interventions to improve RV uptake.