Modern understandings of germ theory and viruses did not yet exist. One “scientific” theory from the 1300s blamed the heavens for the disease, suggesting it was caused by the conjunction of three planets in that year which resulted in a “great pestilence in the air” (e.g., the so-called “miasma theory”). Yes, they had 5G hoaxes then, too. As a consequence, some of the counsel offered by “experts” regarding conduct and response was not the wisest.
Specific locales were affected in different ways. Some would be spared for decades; others experienced repeated outbreaks year after year, especially in cities where folks lived in close proximity and sanitation was problematic. Amsterdam in the Netherlands shows up in records as being “visited” by the plague in 1557, 1558, and 1559—which happens to overlap with some of the fiercest persecution of Anabaptists.
On November 14, 1558, Menno Simons, the emerging leader of Anabaptists, wrote the following to the flock in Amsterdam, from where he was living in Holstein at the time (northeast of Hamburg, along the Baltic seacoast):
“Elect brethren and sisters in the Lord, I hear that the fire of pestilence is beginning to rage in your vicinity…. Be strong in the Lord, be of good cheer, be comforted. For your whole life and death is lodged in the hands of the Lord. All your hairs are numbered, and without Him not one shall drop from your head. The number of your days, nay, your life, is measured as by handbreadths by Him. Therefore do not fear but willingly serve each other in time of need. Oh, do not let the visiting of the sick vex you, for by this you shall be established in love… It is also the nature of true love to lay down our lives for [each other]. 1 John 3:16.”
In our day, we presumably should do our visiting “virtually” or at a social-distance in order to promote safety, but otherwise Menno’s encouragement offers us food for thought as well.
 J. N. Hays, The Burdens of Disease: Epidemics and Human Response in Western History (New Brunswick, NJ: Rutgers Un. Press, 1998), p. 58.
 Rosemary Horrox, The Black Death (Manchester: Manchester Un. Press, 1994), p. 159.
 Andrew Cunningham and Ole Peter Grell, The Four Horsemen of the Apocalypse: Religion, War, Famine and Death in Reformation Europe (Cambridge: Cambridge Un. Press), p. 275.
 Van Braght’s Martyrs Mirror records approximately 60 executions in the 1558, most of them occurring in the Netherlands (pp. 573-591).
 Harold S. Bender, “A Brief Biography of Menno Simons,” in John C. Wenger, ed., The Complete Writings of Menno Simons (Scottdale, PA: Herald Press, 1974), p. 21.
 “Pastoral Letter to the Amsterdam Church,” in Wenger, Complete Writings, pp. 1057-1059.