Study to Evaluate the Safety of 1 New 6:2 Influenza Virus Reassortant in Adults for the 2017-2018 Season

This prospective, randomized, double-blind, placebo-controlled release study will enroll approximately 300 healthy adults 18 to 49 years of age (not yet reached their 50th birthday). Eligible participants will be randomly assigned in a 4:1 fashion to receive a single dose of monovalent vaccine or placebo by intranasal spray. Randomization will be stratified by site. This study will be conducted at 2 sites in the United States of America. Each participant will receive 1 dose of investigational product on Day 1. The duration of study participation for each participant is the time from study vaccination through 180 days after study vaccination.