Vaccination against tick-borne encephalitis (TBE) after autologous and allogeneic stem cell transplantation

•Tick-borne encephalitis (TBE) can result in severe disease in immunocompromised patients.•Four vaccine doses induced seropositivity in a majority (77%) of patients.•We found no safety issues using FSME-immun® after stem cell transplant.•Graft-versus host disease (GVHD) was associated with lower antibody levels.•It seems important to prime patients with four vaccine doses. Our aim was to assess response and side effects of 4 doses of TBE vaccine to patients (pts) after allo- and autologous stem cell transplantation (SCT). PATIENTS: Included were 104 pts with leukaemia, myeloma and lymphoma, median age 61 yrs. METHODS: Vaccine (FSME-Immun®) was given at 9, 10, 12, and 21 months post-transplant. Serum samples were obtained before and after vaccinations. Healthy controls (n = 27) received 3 vaccinations. Assessments of TBE specific IgG antibodies were performed by Enzygnost anti-TBE ELISA test (Siemens, Sweden). Antibody levels (>12 U/mL; “seropositivity”) were seen in 77% and 80% of pts after allo- and autoSCT; IgG levels; 89 vs 94 U/mL. Ongoing chronic GvHD and immunosuppression (n = 29) was associated with sero-negativity in the last sample (p = 0.007). All controls (n = 27) developed protective antibody levels. TBE vaccination was safe, and 4 doses starting 9 months post-SCT, induced seropositivity in a vast majority of pts.