Facilitators and Barriers to Successful Revaccination after Hematopoietic Stem Cell Transplantation among Adult Survivors: A Scoping Review

Vaccination After Haematopoietic Stem Cell Transplant: A Review of the Literature and Proposed Vaccination Protocol

Background/Objectives: Haematopoietic stem cell transplantation (HCT) induces profound immunosuppression, significantly increasing susceptibility to severe infections. This review examines vaccinations' necessity, timing, and efficacy post-HCT to reduce infection-related morbidity and mortality. It aims to provide a structured protocol aligned with international and national recommendations. Methods: A systematic review of current guidelines and studies was conducted to assess vaccination strategies in HCT recipients. The analysis included the timing of vaccine administration, factors influencing efficacy, and contraindications. Recommendations for pre- and post-transplant vaccination schedules were synthesised, specifically for graft-versus-host disease (GVHD), immunosuppressive therapy, and hypogammaglobulinemia. Results: Vaccination is essential as specific immunity is often lost after HCT. Inactivated vaccines are recommended to commence three months post-transplant, including influenza, COVID-19, and pneumococcal vaccines. Live attenuated vaccines remain contraindicated for at least two years post-transplant and in patients with ongoing GVHD or immunosuppressive therapy. Factors such as GVHD and immunosuppressive treatments significantly impact vaccine timing and efficacy. The review also underscores the importance of pre-transplant vaccinations and ensuring that patients' close contacts are adequately immunised to reduce transmission risks. Conclusions: Implementing a structured vaccination protocol post-HCT is critical to improving patient outcomes. Timely and effective vaccination strategies can mitigate infection risks while addressing individual patient factors such as GVHD and immunosuppression. This review highlights the need for tailored vaccination approaches to optimize immune reconstitution in HCT recipients.

Barriers and facilitators to routine revaccination among adult Hematopoietic Cell Transplant survivors in the United States: A convergent mixed methods analysis

BACKGROUND

Hematopoietic cell transplant (HCT) survivorship care includes recommendations for post-HCT revaccination to restore immunity to vaccine-preventable diseases (VPDs). However, not all survivors agree to be vaccinated. No existing studies have comprehensively reported barriers and facilitators to adult HCT survivors completing revaccination.

METHODS

A cross-sectional survey of 194 adult HCT survivors was analyzed using convergent mixed methods. The analysis used various statistical methods to determine the prevalence of barriers and facilitators and the association between revaccination and the number and specific type of barriers and facilitators. Content analysis was applied to open-ended item responses. Integrated analysis merged quantitative and qualitative findings.

RESULTS

The most frequent barriers included the inability to receive live vaccines because of immunosuppression, identifying a suitable community location for administering childhood vaccines to adults, and delayed immune recovery. The most frequent facilitators were having healthcare insurance and a clear calendar of the revaccination schedule. Complete revaccination rates were lower with each additional reported barrier (OR = 0.58; 95% CI 0.459-0.722) and higher with each additional reported facilitator (OR = 1.31; 95% CI 1.05-1.63). Content analysis suggested that most barriers were practical issues. One significant facilitator highlighted by respondents was for the transplant center to coordinate and serve as the vaccination location for revaccination services. Merged analysis indicated convergence between quantitative and qualitative data.

CONCLUSION

Practical barriers and facilitators played a consequential role in revaccination uptake, and survivors would like to be revaccinated at the transplant center.

Financial Burden as a Potential Barrier to Vaccine Completion in Post-hematopoietic Stem Cell Transplant Patients in Japan

Introduction The administration of routine vaccinations to patients following hematopoietic stem cell transplantation (HSCT) is highly recommended. However, studies examining reasons for not completing vaccination in post-HSCT patients are lacking. Method We reviewed the medical records of patients who sought vaccination following HSCT from January 2012 to December 2018 at the Center for Infectious Diseases, Nara Medical University. Results Information regarding patients' backgrounds, administered vaccines, and reasons for not administering recommended vaccines was collected for the study. Thirty-five patients (22 men and 13 women) with a median time from HSCT to the first visit of 25 months were enrolled. Vaccine coverage was highest for diphtheria, tetanus, and acellular pertussis (DTaP) at 89% (31 patients), followed by 23-valent pneumococcal, measles/rubella/mumps, and Japanese encephalitis at 71% (25 patients), 71% (25 patients), and 63% (22 persons), respectively. However, vaccine coverage for hepatitis B, 13-valent pneumococcal, and Hib was low at 26% (three patients), 11% (four patients), and 40% (14 patients), respectively. The reason for not completing the recommended vaccination series was not provided for most cases; however, the economic barrier was cited for all vaccines. Discussion This study identified several cases in Japan where individuals stopped completing post-HSCT vaccinations due to financial constraints. Larger-scale studies may be necessary in Japan in the future for further investigation.