Vaccine hesitancy and routine revaccination among adult HCT survivors in the United States: A convergent mixed methods analysis

Revaccination to restore immunity to vaccine-preventable diseases (VPDs) is essential risk mitigation in the prevention of infectious morbidity and mortality after hematopoietic cell transplantation (HCT). However, revaccination rates have been shown to be insufficient and to what extent vaccine hesitancy contributes to survivors not becoming fully revaccinated is unknown. We performed a cross-sectional, mixed methods survey-based study to explore how vaccine hesitancy influences revaccination among US adult HCT survivors who were 2 to 8 years after transplant. Participants were asked to complete the Vaccination Confidence Scale (VCS) and open-ended survey items regarding vaccine confidence. The survey response rate was 30 %; among 332 respondents, vaccine confidence was high in 69 %, medium in 20 %, and low in 11 %. On multivariable analysis, four factors associated with high vaccine confidence were: predominantly Democrat zip codes (per 2020 election results), ability to pay for revaccination out of pocket, receipt of pre-HCT adult vaccines, and receipt of COVID-19 vaccines. From 189 participants who also answered open-ended items, 14 themes associated with vaccine confidence were identified and collapsed into 4 categories based on the VCS: Benefits, Harms, Trust, and Other. Merged analysis showed congruence between VCS scores and open-ended survey responses and created a narrative about the relative importance of the constructs when approaching revaccination by vaccine confidence level. These findings significantly expand our knowledge of how vaccine hesitancy influences revaccination uptake among US adult HCT survivors. Population-specific interventions to approach vaccine-hesitant survivors should be developed and tested.