Subjects will receive a single dose inoculation of the H3N2 M2SR seasonal monovalent influenza vaccine administered intranasally as a liquid formulation, or placebo (saline). The sentinel subjects will be vaccinated in dose cohort 1 and a safety monitoring committee (SMC) will conduct a review of safety data, tolerability, reactogenicity, and clearance of infectious virus prior to dosing the remaining subjects of the cohort with active or placebo.