Evaluating the Safety and Immune Response to an H5N1 Influenza Vaccine in People Who Have Previously Received an H5N1 or H7N3 Influenza Vaccine and in People Who Have Never Received a Live Attenuated Influenza Vaccine

H5N1 is an influenza virus that has the potential to cause an influenza pandemic. This study will evaluate the safety and immune response to an H5N1 influenza vaccine in people who have previously received one of two versions of an H5N1 vaccine or have previously received an H7N3 vaccine and in people who have not previously received any live attenuated influenza vaccine (LAIV).