I don't usually touch this subject in the wild, but I'll stick this out there. I did a lot of homework, read a lot of medical and white papers and here's what I've discovered. Disclaimer; the Medical Industrial Complex does not endorse this statement.
Melatonin. early research into why age was such a significant contributor to mortality found that Melatonin uses the same ACE-2 receptors that COVID attaches to. Kids have a ton of natural melatonin, after 40 we make far less, and less as we age. Melatonin blocks COVID from attaching. I take 20mg before bed every night; discussing with a friend who has an unspecified congenital lung condition, she and her pulmonologist discovered that 20mg/day of melatonin is actually a known therapy for her condition. I'll save space and tell you that I and a few friends also discovered a marked improvement in lung capacity and ease of breathing after a month. You will feel like a 15 year old kid who sleeps all day for a while. YMMV.
Vitamin D. Get it from the sun if you can. Sweat in the sun and don't wash it off for 3-4 hours. UV rays convert cholesterol in your sweat into Vit-D and you reabsorb that as a lotion; this mechanism is important to know, as the reaction takes place mostly on the surface, not in the skin so if you wash it off you get far less effect.
Zinc. Zinc kills apparently nearly all viruses. But to do that it must be inside your cell walls, so you need to have a steady appropriate diet. Hydroxychloroquine has been in the news since day 1, but nobody wanted to say why; HCQ is an anti-parasitic, but in an unrelated mechanism chemically transports zinc to inside the cells. Even better, Ivermectin does the same, costs less, can be found everywhere (without prescription if you use veterinary Ivermectin and can do the math on dosage). I have apple-flavored horse Ivermectin, $6. I'll take it only if I get infected, though it has been around for 70 years and has zero side effects.
I use Airborne or Emergen-C daily. Airborne works so provably well that the US Military has a NSN part number for it.
I'll not be vaccinated under any circumstance, but that's a different and less friendly thread.