Up your antioxidants. There's a product at the pharmacy Sambucol that is made out of elderberries that is chick full of purple antioxidants, it's been shown to reduce the severity & duration of the flu. Worth getting onto a maintenance dose.

In the meantime, change up your fruit & veg for higher antioxidant fruit & veg (eg have broccoli instead of peas, red cabbage instead of white cabbage, drink grape juice not apple juice, etc). Definitely add in some probiotics too.

If you've been suffering ear/nose/throat lurgs, then get onto the saline spray, stat. Bypass the fess and go straight for one with a higher concentration of salts in it. Alternatively, try doing some oil pulling.