He is the most invoked saint, from the Middle Ages onwards, as a protector from the terrible scourge of the plague, as he cared for many sick people who were miraculously healed by his contact.

His patronage has gradually extended to the world of farmers, animals, major disasters such as earthquakes, epidemics, and very serious diseases; in a more modern sense, he is a great example of human solidarity and Christian charity, in the spirit of volunteerism.

Over the centuries, he has become one of the best-known saints in Europe and overseas.

He died in prison in Voghera because he was believed to be a spy, while he was returning to Montpellier from a pilgrimage to Rome.