My understanding is that the flu is a never ending cycle but you have to start somewhere so in a given period it starts in the Australian winter and heads across the globe, reaching the UK in our winter before going back to Australia for their winter.
Is flu out there anywhere in the world at present?
As Davebro says how can you decide what to put in the mixture this year? That being the case you might end up getting something that would give no protection against this winter's variant -if it ever shows up.