It's not completely baseless. You can't get sick from the cold itself, but lower core body temp does weaken your immune system until you warm up, making it easier for you to get sick if you do get exposed to something.
The cold, dry air during the winter can also dry out the mucus membranes in the sinuses which can make it easier for pathogens to enter the body. Again, doesn't make you sick directly but does interfere with your body's defense mechanisms.
Not only colds, but you also get stiff necks! According to my mother, it's almost instantly. Leaving two windows open makes here neck stiffer than a priest in a kindergarten, but only inside. Standing in the wind outside is perfectly fine.
Also Russia and probably most eastern European countries. One of my kids will catch a cold and the first thing my mother or grandmother will ask is if they were somewhere drafty.
Sei froh! Wenn sie die Fenster nur kippen würde wärt ihr wahrscheinlich schon tot oder zumindest schwer krank. Soweit ich weiß ist so ein kleiner Zug, den man kaum spürt, am gefährlichsten. Weil dann fühlt sich der Körper sicher und Killerviren haben leichtes Spiel!
I didn't know it's a thing in Germany too. 😊 Drafts are also blamed for pretty much any unexpected ailment, from rheumatism to toothache. And off course cold, flu and so on.
Yeah, but then they go and open all the windows to "change the air" no matter the weather.
I used to work with a bunch of Germans in the US. I came in to the office one time at about 4:30am in February. One of the guys had all the windows open when the outdoor temperature was something like -20F.
Like Moritz, I think that avoiding the draft is more important than changing the air at that point. 🙄
I also had an old manufacturing guy tell me that drinking cold water in the summer would kill you because of the shock to your system.