Safety of influenza vaccine in heart transplant recipients

Background: Influenza vaccine is recommended for heart transplant recipient s, but its administration is often deferred because of anecdotal reports of rejection associated with the vaccine. We evaluated the safety of influenz a vaccine in a group of stable heart transplant recipients over a 2-year pe riod. Methods: During the 1993 to 1994 influenza season, stable heart transplant recipients who had undergone transplantation a minimum of 1 year before stu dy entry were randomized to vaccination with a single dose of influenza vac cine versus no vaccination. Routine endomyocardial biopsies and postvaccina tion influenza serologic studies were performed between 2 and 6 weeks after enrollment/immunization. During the 1994 to 1995 season, patients were giv en 2 doses of influenza vaccine, separated by 3 weeks; endomyocardial biops ies and serologic studies were performed between 2 and 6 weeks after the se cond immunization of enrollment (if control subject). Biopsy results were e valuated with respect to vaccine response, immunosuppressive regimens, and patient demographics. Results: Eighteen patients were enrolled in the single vaccine trial and 10 in the booster vaccine trial. Four of 14 vaccine recipients had biopsy spe cimens consistent with International Society for Heart and Lung Transplanta tion grades 2 to 3A as compared with 1 of 14 control subjects (grade 2) (p = .326). All episodes of rejection in the vaccine recipients were asymptoma tic and responded to a single course of treatment. Rejection was unrelated to the time from transplantation doses of immunosuppression, age, or number of doses of or response to vaccine. Conclusions: Influenza vaccine can be safely administered to most heart tra nsplant recipients but may be associated with low-level histologic rejectio n.