-snip-
I looked into this.
The vitamin C "method" is controversial. Author's of this meta study (which seems to be regularly updated from what I found)
https://www.cochranelibrary.com/cdsr/doi/10.1002/14651858.CD000980.pub4/abstract
found no evidence of benefits of vit C AFTER the onset of symptoms. Before the infection it might be helpful.
The main point that I want to make is:
STAY THE FUCK AT HOME wherever possible.
This is the most important thing to do. Don't feel any safer because you're supplementing yourself with vitamins. Wash your hands as the first thing you do when coming home. Change your clothes, don't throw clothes from the outside around. Everything that comes from outside should be stored at a fixed place, best case even in sunlight or at least a warm and dry place. And don't touch your face when you're outside. This is where even a scarf in front of your face helps, because it reminds people of not doing it.