I don’t know about HCQ vs Ivermectin, but I too have been doing the C, D & zinc since Mar 2020. I did get a sinus infection last month - like a fool I tried cutting back - only 1 week instead of 2 usually and went back and forth from feeling good then lousy once I got back on the daily regimen.
The other thing I felt truly boosted my immune system was 8 eight oz glasses of water (tea or coffee also) per day.
Thanks - I had gotten slack about my vitamins, etc., too. it’s easy to get complacent when we’re busy :-/