The seat of the Papacy had been moved from Rome to Avignon in the early part of the fourteenth century, and now Pope Clement VI occupied the post. As the spiritual leader of all Christendom, Clement decided he would be no use to anyone if he died, so he made it his business to survive. His physicians helped matters along by insisting he remain isolated and keeping him toasty-warm between two roaring fires -- in the dead of summer.
Clement may have had the fortitude to withstand the heat, but the rats and their fleas didn't bother, so the pope remained free of plague. Unfortunately, no one else had such resources, and one quarter of Clement's staff died in Avignon before the disease was done.
As the pestilence raged ever more fiercely, and people died too swiftly to receive last rites from the priests (who were dying, too), Clement issued a decree stating that anyone who died from the plague would automatically receive remission of sins, easing their spiritual concerns if not their physical pain.