I’m an anti-vaxer and so is my MD.
He prescribes 1 pharmaceutical pill for me and 12 nutritional supplements. We both believe in prevention. In fact, I wrote for a magazine called “Prevention” decades ago did a ton of research. One immune system strengthener is Vitamin C. I’m very small, so take only 500 mg per day. My big, overweight make friend takes three times that much..
Be careful with Vit C. Too much can lead to kidney stones.