Safety and Efficacy of Two Types of Influenza Vaccination in Heart Transplant Recipients: A Prospective Randomised Controlled Study

Influenza may cause severe disease in immunosuppressed patients. Different vaccines have been proved to be efficacious to prevent influenza in tranplant recipients. Since the last five years the addition of adjuvants to improve the immune response to vaccine preparations has been proposed and evaluated. In this study, two antigenically identical vaccines, but different for the presence of adjuvants were randomised among a cohort of heart transplant recipients to evaluate their safety and immunogenicity. 58 patients, receiving an heart transplant more than 6 months before, were randomised to receive one shoot vaccination with Fluad (containing the MF59 adjuvant) or Agrippal (no adjuvant added) or to enter the control, not-vaccinated, group. The immune response to influenza was evaluated separately for type A and type B viruses and for the IgG and the IgM antibodies. Patients were clinically evaluated at least monthly up to 6 months. Influenza symptoms were reported by 33% of patients receiving Fluad, 29% of the Agrippal and 63% of the control group. 4 episodes of acute myocardial rejection ≥3A were identified without difference between the three groups. The superior efficacy of vaccines containing adjuvants was not found and the data clearly confirmed that vaccination against influenza is safe and effective in heart transplant recipients. The use of vaccine containing adjuvant substances do not ameliorate the clinical performance of the immunisation suggesting that less expensive influenza vaccine preparation without adjuvant substances could be equally useful to protect heart transplant recipients.