You can go to the drugstore right now and get Quercetin 500 mg, Vitamin C 1000 mg, Zinc 50 mg and Vitamin D3 125 mcg. Taking one group of those in the morning and one in the evening will boost the immune system.
Hubby and I were exposed to omicron last week, and this is what we're taking. He's been sick but not too severe. I haven't been sick at all. This, along with NAC and melatonin also got me through a round of COVID last winter. Mild illness - no respiratory problems. The friend who was exposed with me spent a month in the hospital, complete with Remdesivir. I take vitamin D3 every winter for mood and immunity.
I recommend people get a home pulse-oximeter to monitor oxygen levels. They're about $30 and typically available at the drug store. I don't know how the supply chain issues have affected availability though. Our drug stores have a lot of empty and half empty shelves these days.