Decreased Antibody Response to Influenza Vaccination in Kidney Transplant Recipients: A Prospective Cohort Study

Background: Antibody response to the inactivated influenza vaccine is not well described in kidney transplant recipients administered newer, but commonly used, immunosuppression medications. We hypothesized that kidney transplant recipient participants administered tacrolimus-based regimens would have decreased antibody response compared with healthy controls. Study Design: Prospective cohort study of 53 kidney transplant recipients and 106 healthy control participants during the 2006-2007 influenza season. All participants received standard inactivated influenza vaccine. Setting & Participants: Kidney transplant recipients administered tacrolimus-based regimens at a single academic medical center and healthy controls. Predictor: Presence of kidney transplant. Outcomes: Proportion of participants achieving seroresponse (4-fold increase in antibody titer) and seroprotection (antibody titer >= 1:32) 1 month after vaccination. Measurements: Antibody titers before and 1 month after vaccination by means of hemagglutinin inhibition assays for influenza types A/H1N1, A/H3N2, and B. Results: A smaller proportion of the transplantation group compared with the healthy control group developed the primary outcomes of seroresponse or seroprotection for all 3 influenza types at 1 month after vaccination. The response to influenza type A/H3N2 was statistically different; the transplantation group had 69% decreased odds of developing seroresponse (95% confidence interval, 0.16 to 0.62; P = 0.001) and 78% decreased odds of developing seroprotection (95% confidence interval, 0.09 to 0.53; P = 0.001) compared with healthy controls. When participants less than 6 months from the time of transplantation were considered, this group had a significantly decreased response to the vaccine compared with healthy controls. Limitations: Decreased sample size, potential for confounders, outcome measure used is the standard but does not give information about vaccine efficacy. Conclusions: Kidney transplant recipients, especially within 6 months of transplantation, had diminished antibody response to the 2006-2007 inactivated influenza vaccine. Am J Kidney Dis 54:112-121. (c) 2009 by the National Kidney Foundation, Inc.