Include ORGANIC, UNREFINED COCONUT OIL in your diet---coconut oil is loaded with lauric acid, which is effective against viruses, as well as being anti-bacterial. Use it when sauteing vegetables, put it in your coffee or tea, use it in soups or stews.
QUERCETIN is a plant pigment that is an antioxidant, & it has anti-viral properties. The best way to get it is to eat foods high in quercetin. Foods high in quercetin include:
  Red Onions—BEST source
  Organic apples, grapes, and tomatoes
  Dark berries like cherries, blueberries, and blackberries
  Taragon, chives, coriander, and dill
  Spinach and kale 
 AVOID SUGAR in all forms. Sugar suppresses our immune system.
 ---The amount of sugar in one soft drink suppresses immune function for up to 12   hours.
  ---There is a 50% decrease in the effectiveness of your white blood cells to fight   infection for up to 4 hours after eating just 2 teaspoons of sugar.
 ---Read labels; divide the number of grams of sugar by 4 to tell how many    teaspoons of sugar a product contains.
VITAMIN D is a key nutrient for supporting immune function. Your body makes Vit D  when you’re exposed to natural sunlight, so try to spend some time outdoors. You can  supplement with Vit D---4,000 or 5,000 iu (international units) is recommended per day. Have your Vit D status checked if possible, and in the meantime get it in foods rich in Vit D, such as fatty fish (tuna, salmon, herring, sardines, mackerel), egg yolks, and mushrooms.