Good old garlic has strong anti-viral properties. So has tea tree oil but don't drink it. Maybe gargle with it or steam under a towel, if you are not allergic to it.
Ginger should be good too. I went to my local Tesco and Morrisons superstores, all garlic and ginger was gone. People know something
Bacillus Subtilis pro-biotic bacteria found in Natto (Japanese fermented soy beans) and some Lactobacillus bacteria found in pro biotic yogurts produce anti-viral compounds of equivalent strength to Tamiflu according to some research articles.
Red peppers have 120mg vitamin C per 100g, more than oranges.
Eat healthy and stay safe.