I read a few alternative health letters written by doctors who practice holistically. The majority (all) seem to feel that the yearly flu shot offers little to no protection. It is pretty impossible task set for those who try to predict which strain(s) of flu will be most prevalent the following flu season. So it is rather like a gamble by pharmaceutical companies who make the flu shots from the viruses they think will spread disease next flu season. Then they hope that they will prove to be effective, because they have guessed correctly. If they have guessed incorrectly the flu shot is not effective against that year's flu epidemic.
On the conventional side I have read that getting a flu shot may help reactivate the immune system of those who are more elderly. Sounds more like a sales pitch though to the elderly. Hmm, wonder what it does to the very young immune system then? Some claim flu shots harm the immune system of young children. Then there is the mercury and some say aluminum that vaccines may contain. Some discussions of vaccines, for and against.
Comments for and against flu vaccines:
Which Is Worse, Influenza Or The Vaccine? | Live Fit Blog
Here is a researcher who claims that flu shots do not work balanced by a conventional doctor from Canada who says they do:
Not enough proof that flu shots work, researcher warns
Many see flu shots as a way for pharmaceutical companies to make money (and no doubt that is very true) especially if it is a forced issue in the school systems, no child left behind when it comes to vaccinations including flu vaccinations:
CDC: Immunize Every Kid in America Against Flu - Every Year! Hey, It Worked in NJ!