According to boccaccio, what did some people believe to be the cause of the plague?

According to Boccaccio, some people believed that the reason for the plague was their own sins. In the year 1348 there was huge death in Florence due to plague. People believed that God had punished them for their sins. Healthy people distanced themselves from those suffering from plague. The healthy people tried to remain safe by leading a normal life without much luxury. They used to remain in groups, separated from those that were suffering. Many animals also died because of this plague.