My lil girl is 5 and in kindergarten what month should she getvthe flu vaccine and how long does it last?

Flu vaccine: Flu vaccine should be given to everyone over six months of age to prevent the most common forms of influenza expected that year. Since influenza strains change rapidly, the flu vaccine is given every fall and contains a new combination of strains. Bonus: in a healthy five year old, the nasal spray vaccine can be given. No needle.