Not showing up in modern textbooks…..
I just sent you a mail about travelling and masks and I will attach below this mail again.
Sending you now the most logic story about the common cold which a textbook of the sixties described with a simple conclusion but this is not mentioned in a textbook of 2018 [basically nothing changed]
Travelling? https://bdmesq.wordpress.com/2021/07/18/travelling/ via @bdmesq