I won't, neither will my family
but only because I found this as a starting point:http://drtenpenny.com/VitaminD_info.aspx
At the bottom of the page is dosages for Vitamin D as a reference. I realize that D3 isn't the only thing to do to lower my risk, and that of my family's, of coming down with the flu but it helps.
So for me, I decided against the flu shot because I had other alternatives. It also helps in social conversation when others are die-hard flu shot promoters, that I can just smile and say, "I don't think my family will be getting the flu shot... or the flu, this year. Thanks."
Good luck with your decision! It took me years of research prior to and immediately after having my first kid (2.5 yo now) to be 100% okay with non-vaccing. And I'm okay with checking in and reevaluating my decision all the time.