Safety of and Immune Response to Recombinant Live-Attenuated Influenza H6N1 Virus Vaccine Vaccine

Inclusion Criteria: * Adult males and non-pregnant females 18-49 years old * General good health * Available for the duration of the trial * If female, agree to use effective birth control methods for the duration of the study. More information on this criterion can be found in the protocol. Exclusion Criteria: * Evidence of clinically significant neurologic, cardiac, pulmonary, hepatic, rheumatologic, autoimmune, or renal disease. More information on this criterion can be found in the protocol. * Behavioral or cognitive impairment or psychiatric disease that, in the opinion of the investigator, intereferes with the study * Previous receipt of FluMist or any intranasal live attenuated influenza vaccine * Previous enrollment in an H6N1 influenza vaccine trial or in any study of an avian influenza vaccine * Seropositive to the H6N1 influenza A virus (serum HAI titer \>1:8) * Positive urine drug toxicology test indicating narcotic use and/or dependency as defined by the Drug Enforcement Agency * Medical, occupational, or family problems as a result of alcohol or illicit drug use within the 12 months prior to study entry * Any condition that, in the opinion of the investigator, would interfere with the study * History of anaphylaxis * Allergy to oseltamivir as determined by subject report * Current diagnosis of asthma or reactive airway disease within 2 years prior to study entry * History of Guillain-Barre Syndrome * HIV-1-infected * Hepatitis C-infected * Positive hepatitis B virus surface antigen * Known immunodeficiency syndrome * Use of corticosteroids (excluding topical preparations) or immunosuppressive drugs within 30 days prior to study entry * Receipt of a live vaccine within 4 weeks or a killed vaccine within 2 weeks prior to study entry * History of a surgical splenectomy * Receipt of blood or blood-derived products (including immunoglobulin) within 6 months prior to study entry * Current smoker unwilling to stop smoking for the duration of the study. More information on this criterion can be found in the protocol. * Travel to the Southern Hemisphere within 14 days prior to study entry * Travel on a cruise ship within 14 days prior to study entry * Direct contact with live poultry within the 14 days prior to the study or after study completion. * Receipt of another investigational vaccine or drug within 30 days prior to study entry * Allergy to eggs or egg products * Pregnant or breastfeeding