Fun fact. Immigration was kept open across Europe during the plague. Poland was an exception and kept their borders closed. They were subsequently spared the ravaging death toll.

“One theory was that Poland’s ruler at the time, Kazimierz the Great, effectively quarantined the whole country by banning all foreigners from crossing the kingdom’s borders, thereby restricting the movement of people who were affected.”

https://www.thefirstnews.com/article/no-way-no-plague-was-po...