That’ll be the seasonal cold that’s circulating at the moment. Until the pandemic it was par for the course when people mix in confined spaces with no or recirculating aircon. My son has it as he works in a pub.
No harm in getting some extra vitamins in though!
Unusually for me, I have had some sniffles in the last week or so. Pretty trivial so far, I have not bothered with any medication either. Fair number of people in the real world complaining or commenting on it.
On the rare occasion that I get a cold I usually rely on traditional treatments, couple of pints of strong ale and a curry one level hotter than I would usually have generally does the trick.