This randomized, double-blind, multi-center study will enroll approximately 200 children 24 to < 48 months of age. Subjects will be randomized in a 1:1:1 ratio to receive two doses of either FluMist quadrivalent 2017-2018, FluMist quadrivalent 2015-2016 formulation, or FluMist trivalent 2015-2016 formulation.