SUMMARY The Stanford-LPCH Vaccine Program is seeking healthy 18-30 years old to take part in an influenza (commonly known as "the flu") vaccine study. In this study, we will be looking at the differences in the immune response between three types of licensed seasonal flu vaccines. You will be randomly assigned to receive a single dose of the flu vaccine either in the arm (an intramuscular or intradermal flu shot) or the nasal spray flu vaccine. All vaccines are licensed by the FDA and are not experimental. These are the same seasonal flu vaccines that will be used for the public during the fall flu season. We will compare the B-cell responses by analyzing vaccine-induced plasmoblasts, their immunoglobulin gene-repertoire and functions of polyclonal antibodies and recombinant monoclonal antibodies derived from these cells. The research will be conducted at Stanford University by Dr. Cornelia L. Dekker, M.D., Professor of Pediatrics at Stanford (Stanford-LPCH Vaccine Program) and Mark Davis, Ph.D. (Institute of Immunity Transplantation and Infection) To be eligible, you must not have received a flu immunization last year (2010-2011) and should be: Healthy Age 18-30 years old Able to attend 3-4 clinic visits at Stanford within a one month-period (Sept - Dec) Able to provide 3-4 blood samples If eligible, you will receive: The current seasonal flu vaccine (2011-2012) $30 per clinic visit Parking vouchers ELIGIBILITY: To review the complete list of eligibility requirements and to learn more about the visit schedule for this study, please click this link: ** Eligibility Criteria and Visit Schedule ** For further information or to volunteer: Please contact the Stanford-LPCH Vaccine Program at (650) 498-7284 or email us at