Today, as recounted by the entry on Madonna della Salute at the blog "Venice from beyond the bridge", is Venice's locally observed feast day of Our Lady of Health.
Every Italian city is allowed one local holiday. But since that of the Venetian patron saint, Saint Mark, is the 25th of April and just happens to coincide with the Italian national holiday celebrating "Liberation Day" at the end of World War II, Venice gets to choose another local holiday to observe. It selected that of the Madonna della Salute, founded to commemorate the end of a massive epidemic of plague that began in 1630 and culminated in the construction of the glorious basilica dedicated to the Madonna who was credited with eventually saving the city from the plague.
Today, Venetians don't fear the plague, but many of them still make a pilgrimage to the Basilica to light a candle to the Madonna on this day. Tradition has it that those who do will not get the flu this winter. One year, the cousin of the father of my Venetian husband (say that three times fast!) stopped us on the street on November 21st and asked us whether we were going to the church ourselves. When we said we weren't planning to, she was shocked. "One GOES to the Salute," she insisted.
Best wishes to all for a healthy winter on this feast day of the Madonna della Salute!