You want to enhance your immune function. Sometimes this is not a good idea in certain disease. For example if you already have COVID and are very ill- I would not suggest to enhance your immune system However if you want to stay healthy and not get COVID 19 then you should enhance your immune system
We know a good diet with few if any simple carbohydrates should be adhered to as well as some exercise program.
There are some supplements that you should take
Vitamin D3 - all should supplement at this time You can ask your doctor to do a Vitamin D3 serum level You want to be in the 60 range
Melatonin - this supplement is not only used for sleep. In my cancer patients I recommend 20 mg . Drinking cherry juice can increase your melatonin levels. On teaaspoon of raw honey can also increase your own melatonin levels
Mushrooms can stimulate innate anti viral activity. These medicinal mushrooms can be turkey tail, lions mane, shitake , coryceps, and more. I usually recommend a mushroom formula by Paul Stammetts- Host Defense.
Vitamin A and Zinc - I would only use these two supplements if you have had a serum levels checked by your health care provider. Vitamin A like Vitamins D, E and K are fat soluble and cause increased liver enzymes if take too much