Answer:
During the plague, also known as the Black Death, around a third of the population of Europe died, the rate varying among the different European regions, with some losing over half of their population, and others losing less than a third.
Jewish communities overall had much better results in terms of mortality, due to their superior sanitation and hygiene. However, many non-jews saw this as a supposed proof that the Jewish people had caused the Black Death, for example, by poisoning the wells. This wrong beliefs spread over many communities and led to the persecution of Jews, and the killings of many of them.