In … 1519 the plague appeared in Switzerland. As it had not yet come to Zurich, Zwingli went on a holiday that summer to Pfaefers, about sixty miles south-east of Zurich. In the village was a large Benedictine monastery, in which he probably stopped. There Zwingli was when the news reached him that the plague had broken out in Zurich.
As it was the duty of the people’s priest to be on service in the city during plague time, he hastened back, and did his duty faithfully. The plague was very severe, for 2500 died of it out of an aggregate population in the three parishes of only 17,000. It broke out on St. Lawrence’s day (Wednesday, August 10, 1519), reached its height September 12th, and subsided in Christmas week, yet lingered for a year after that.
Zwingli fell a victim toward the end of September, and was very sick. By November he was able to write again. But his recovery was slow. On November 30th, he complains that the disease had left his memory weakened, his spirits reduced, so that his mind wandered when preaching, and after preaching he felt thoroughly exhausted. On December 31st, he reported himself as well again, and that the last ulcer caused by the malady had healed.
But his rejoicing was premature, as on March 27, 1520, he complains that he had eaten and drunk many drugs to get rid of his fever, and still his head was weak, although he was daily growing better.*
Zwingli never shirked his duty, never fled the scene, never acted out of fear or in a quest for self preservation. Always his eyes were on the Church for which he felt an all encompassing responsibility. Even if he was wrong on things from time to time, his motives were always stellar.
S. Jackson, Huldreich Zwingli: The Reformer of German Switzerland (1484–1531),(pp. 131–132). New York: G. P. Putnam’s Sons.