It’s not yet clear what makes the new variants more contagious. They share at least one mutation, called N501Y, that is thought to be involved. One possibility, researchers said, is that the mutation may increase the amount of virus in the nose but not in the lungs — potentially explaining why it is more contagious, but not more deadly.A higher amount of virus in the nose means anyone infected would expel more virus while talking, singing, coughing or even breathing, said Trevor Bedford, an evolutionary biologist at the Fred Hutchinson Cancer Research Center in Seattle