Flu vaccines here in the U.S. often contain a toxic cocktail (CDC additives page) of aluminum, MSG, or even mercury and can therefore impair your immune system, making it more likely that you'll get influenza. Most people suffering with the flu right now are people who were already "vaccinated" against the flu.
Fortunately, you can find many homeopathic and naturopathic alternatives to the flu shot for prevention and to ease symptoms if you do contract the flu. Both prevention and treatment alternatives include: Vitamin D and Vitamin C supplements, Elderberry extract, and Echinacea. Look here , here, and here for more detailed information.
For prevention, remember to get plenty of sleep, wash your hands frequently, and sneeze/cough into your arm and not your hands. Also, you should be eating a mostly vegetarian diet, high in whole grains, buying as much of your food organically grown as you can, and limiting alcohol. Stay healthy!