i have never experienced so many colds,virus when i use to do nursing years ago. I think that a close environment
promotes that and it is quite common in hospitals and care homes,offices bla bla.....
What your mum,like my mum, are always making those comments based on old wise tales.
like "you must not make jam , or wash your hairs during your periods! "that is a good one!
To avoid colds and the like have a good diet, and include a lot of garlic in your cooking , but stay away from anybody with a snoty nose.