ABSTRACT
Hematopoietic stem cell transplantation (HCT) survivors are less likely than matched healthy controls to mount a strong immune response to trivalent inactivated influenza vaccine (TIV). High-dose (HD) or standard-dose (SD) TIV were given to adult HCT subjects 18 years or older at least 6 months after transplantation. Subjects were randomized 2:1 to receive either the HD (60 µg hemagglutinin [HA]/strain/dose) or the SD (15 µg HA/strain/dose) TIV. Injection-site and systemic reactions were documented after each vaccination and immune responses were measured before and after each vaccination. A total of 44 subjects were enrolled (25 in year 1 and 19 in year 2), with 15 in the SD group and 29 in the HD group. The median time to vaccination after transplantation was 7.9 months (range, 6 to 106 months), the median age was 50 years (range, 19.6 to 73 years), and 61% were male. No differences in demographic or lab data were noted between groups; however, the HD group had higher median baseline total IgG level (676 versus 469 mg/dL, P = .025). No differences in individual injection-site or systemic reactions were noted between groups; however, more events of any injection-site symptom combined were reported in the HD group. No serious adverse events were attributed to vaccination. After vaccination, the HD group had a higher percentage of individuals with titers ≥1:40 and a higher geometric mean titer (GMT) against the H3N2 strain compared with that of the SD group. HD and SD TIV were found to be safe and well tolerated in adult HCT recipients. However, the HD group had higher frequency of injection-site reactions but the majority of the reactions were mild and resolved. The HD group had a higher percentage of individuals with post-vaccination titer ≥ 1:40 and GMT for H3N2 antigen, indicating better immunogenicity. These data support the need for a phase II immunogenicity trial in HCT recipients.
