Associations Between Demographic Factors, Clinical Variables, Social Determinants of Health, Vaccine Hesitancy, Vaccine Behavior, and Revaccination Status: A Survey of Adult HCT Survivors in the United States

Abstract

Comprehensive survivorship care after hematopoietic cell transplantation (HCT) includes revaccination to restore immunity to vaccine-preventable diseases (VPDs). There is complexity to revaccination in this setting, and revaccination rates are sub-optimal. HCT survivors are at high-risk for morbidity and mortality from infections including VPDs, underscoring the importance of interventions to improve revaccination rates among survivors. Determining associations between survivor characteristics and revaccination uptake may guide interventions. The overall study objective was to advance our understanding of factors influencing revaccination uptake among adult HCT survivors living in the United States The specific study aims were to: (1) determine the prevalence of adult survivors who are completely, partially, or not revaccinated at 2 to 8 years after HCT and (2) examine associations between demographic variables, social determinants of health, clinical variables, past vaccination behaviors, vaccine hesitancy (Vaccination Confidence Scale), and revaccination status in adult HCT survivors. This study employed a one-time cross-sectional revaccination survey of adults who were surviving 2 to 8 years after HCT and living in the United States. The survey was sent to eligible survivors in the Fred Hutchinson Cancer Center Long-term Follow-up research cohort. The point prevalence of revaccination outcomes was determined from all the respondents (n = 338), differences in intent to revaccinate for people not yet fully revaccinated were explored using Fisher's exact test (n = 126), and associations were examined between revaccination outcomes and predictors using multivariable logistic regression (n = 292). Survey response rate was 30%. Among respondents, 62% were completely revaccinated, 33% were partially revaccinated, and 4% were not revaccinated. Most respondents (77%) who were not yet fully revaccinated planned to complete the revaccination protocol. However, fewer not-revaccinated respondents than partially revaccinated respondents planned to complete revaccination (50% versus 80%, P = .032). Factors associated with incomplete revaccination were shorter time from HCT, inadequate immune reconstitution, and not having received all childhood vaccines as a child. Our analysis has identified multiple variables associated with revaccination outcomes, indicating the potential for interventions to enhance post-HCT revaccination rates. Since many survivors cannot be revaccinated promptly due to delayed immune recovery, clinicians should iteratively re-evaluate for revaccination readiness as long as it takes to ensure eventual revaccination. Broader efforts by the healthcare community to increase childhood vaccine uptake might eventually support revaccination uptake. Future research that builds on these findings should focus on intervention testing.

Keywords: Hematopoietic cell transplant survivors; Revaccination; Social determinants of health; Vaccine hesitancy; World Health Organization Behavioral and Social Drivers of Vaccination (BeSD) Framework.