The Delta variant is here. “We’ve been warned three times by the U.K.,” Topol says, referring to previous surges in early 2020 and last winter. “This time is the third warning.”There is some indication that the Delta variant may also result in more severe disease. Several experts said they do not expect the Delta variant to cause a nationwide surge here in the U.S. like the one that occurred last winter. A new version of the Delta variant called “Delta Plus” is already circulating.