I have had Common Cold only once ever since. This was because I wanted to read one Knut Hamsun's book and it was not available on Pirate Bay. I did not realize I was quite receptive to a virus on a book.
I also invented the use of some kind of anti-viral agent all on my own. I read about amoebas entering the brain in India, so I started to use a drop of household bleach. But I later resorted to to Betadine-Povidone because you cannot have all sorts of stuff in your backpack.
Anyways in Finnish Army Guerrilla Book you need only one drop of bleach for every 250 ml, and 24 hrs, to make it totally safe for any kind of use.
But in this Covid-era I have been flushing everytime I been exposed to humans in tight spaces. Luckily I have in my neighborhood very unpopular and expensive food market with no other customers.