The three supplements that are cheap and effective at boosting your immune system in this time of Covid. They are Vitamin C 1000 mg two time a day, Lysine 500 mg twice a day and zinc 60 mg one time a day. These three are a good baseline to supplement before you have symptoms or you are just starting to get sick. There are many more things in the nutritional arsenal but starting simple is certainly helpful to boost your own immune response to infection.