Study to Evaluate the Safety of 3 New 6:2 Influenza Virus Reassortants in Adults

This prospective, randomized, double-blind, placebo-controlled release study will enroll approximately 300 healthy adults 18 to 49 years of age. Eligible subjects will be randomly assigned in a 4:1 fashion to receive a single dose of trivalent vaccine or placebo by intranasal spray. Randomization will be stratified by site. This study will be conducted at 3 sites in the United States of America. Each subject will receive 1 dose of investigational product on Day 1. The duration of study participation for each subject is the time from study vaccination through 180 days after study vaccination.

Inclusion criteria

• Age 18 through 49 years
• Written informed consent
• Subject available by telephone
• Ability to understand and comply with the requirements of the protocol, as judged by the Investigator

Exclusion criteria

• Concurrent enrollment in another clinical study up to 180 days after receipt of investigational product (Day 181)
• History of hypersensitivity to any component of the vaccine, including egg or egg protein or serious, life threatening, or severe reactions to previous influenza vaccinations
• Any condition for which the inactivated influenza vaccine is indicated, including chronic disorders of the pulmonary or cardiovascular systems (example [eg], asthma), chronic metabolic diseases (eg, diabetes mellitus), renal dysfunction, or hemoglobinopathies that required regular medical follow-up or hospitalization during the preceding year
• Acute febrile (greater than [>] 100.0 degrees Fahrenheit [F] oral or equivalent) and/or clinically significant respiratory illness (example, cough or sore throat) within 14 days prior to randomization
• Any known immunosuppressive condition or immune deficiency disease, including human immunodeficiency virus infection, or ongoing immunosuppressive therapy
• History of Guillain-Barré syndrome