Here are some ways to strengthen your immune system to fight of that nasty flu.
Increase your nutrient intake, especially the following:
All of the vitamin Bs
Try taking echinacea and shitake mushroom supplements
Take Sambucus. It's black elderberry juice and studies have shown it to have high antiviral properties and to be as effective as the antiviral medications.
Get plenty of rest.
Drink a lot of water.