Why Is There A Winter Flu Season? A series of info-graphics attempts to explain..

I have been researching this for a while. I was sure there was an answer.
And then I realized, there are a ton of answers and endless possibilities as to why there is even a flu season to begin with.
And with all the possibilities, I will add one more in the mix: The flu shot. It seems that whenever there is a hot and heavy campaign to vaccinate people against the flu, the flu suddenly spreads.
Coincidence, I am sure I’d be told. Coincidence. 
Now excuse me while I pop my vitamin D supplement.