Vaccination Uptake in Adults Post‐Haematopoietic Stem Cell Transplantation for B‐Cell Malignancies

The interesting article by Buvelot et al. on offering individualised approaches to improve vaccination responses post haematopoietic stem cell transplant (HSCT) in children 1, may equally be relevant to adults. In a recent publication, Paternina-De La Ossa et al. showed that two-thirds of patients responded to immunisation against diphtheria and tetanus with slightly more than half responding to the pertussis component 2. However, 30% of their patients had missed appointments or were lost to follow-up and therefore potentially immunologically vulnerable. Vaccination uptake in HSCT recipients remains consistently suboptimal in published literature, with reported completion rates < 50% at 24 months post-transplant 3, 4. With such low uptakes, would individualised approaches work? We sought to assess compliance against 2023 Joint Consensus Statement guidelines among adult patients who underwent HSCT for B-cell malignancies at Hull University Teaching Hospitals NHS Trust 5. Patients were identified using the Haematology Cancer Database who underwent HSCT with BEAM conditioning (January 2021–December 2022). Data were collected retrospectively using digital records. Variables included patient demographics, date of vaccination commencement, completion of all recommended non-live vaccines and compliance with avoidance of live vaccines for 24 months post-HSCT. Twenty-eight patients aged 17–68 years mean ± SD 48.8 ± 16 years underwent HSCT in the 24-month period, of whom 6 were excluded (4 died before vaccine initiation, 2 non-B-cell malignancies). Malignancy subtypes: Hodgkin's disease (n = 10), mantle cell lymphoma (n = 5), follicular lymphoma (n = 3), diffuse large B-cell lymphoma (DLBCL) (n = 1), CNS lymphoma (n = 1), plasmablastic lymphoma (n = 1), extra-nodal marginal zone lymphoma (n = 1). Overall survival during audit (February 2024) was 68%. Of the 22 patients, 86.36% had commenced re-vaccination at 6 months post-HSCT, but only 41% completed all recommended non-live vaccines by 24 months. There was 100% compliance regarding avoidance of live vaccines. Uptake varied across individual vaccines, with decreasing order of adherence from Men ACWY (79%), COVID-19 vaccines (73%), Td-IPV, first dose PCV13 (conjugate pneumococcal) and annual influenza (68%), HiB and Men C (64%), to lowest for the second PPSV23 (polysaccharide pneumococcal) dose (60%). The lower uptake of the second PPSV23 booster is consistent with published data demonstrating reduced adherence to multi-dose schedules later in vaccination timelines 3. Ahmad et al. showed that 48% of patients completed all vaccinations by 24 months post-HSCT 4 and Ariza-Heredia et al. reported an overall compliance rate of 60% 1-year post-HSCT 6. Both concluded that missed vaccinations could be attributed to immunosuppressive therapy, referral to primary care, or administrative gaps. These concordant findings across multiple centres underscore the systemic nature of this challenge. We identified a high commencement rate (86%) that was offset by a low completion rate (41%) revealing a clinically important gap between initiation and full schedule completion. How will individualised approaches through primary care for vaccine delivery work better, being particularly pertinent for the United Kingdom, as currently this shows greater potential for coordination failures and missed doses? A multi-faceted approach encompassing improved patient communication through enhanced digital record-keeping (patient access and reminders) and continuous engagement between specialist and primary care teams to increase vaccine uptake will ultimately lead to improved long-term patient outcomes. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.