 Potentially eligible patients will be screened for the FLUVAC study during an ESPRIT follow-up visit. Those who are eligible and agree to participate will have 10 ml 1 tablespoon of blood drawn to assess baseline antibody levels and then receive the vaccination. They will be vaccinated annually for 3 years. A blood sample 10 ml will be drawn 1 month after each vaccination to measure the immune response. Some of the blood drawn for this study will be stored and used for research purposes. 