it's true the mix of strains in the flu shot is a crapshoot. has to do with the time required to grow the viruses in eggs and manufactor the vaccine from the eggs. MDInana, feel free to correct me if I'm wrong.
M_a_x, hope you're using sterile water or sterile saline for that can. There's a particularly nasty strain of amoeba which can be found in some tap water and has been implicated in some lethal meningitis cases where people used tap water for nasal irrigation.