The Health 202: Delta variant cases are surging, and experts say it’s hard to forecast how much worse it could get

In comparison, the United States has a lower vaccination rate. Just under 50 percent of Americans are fully vaccinated. And the United States is a much larger country, so even as surges end in one part of the country, they often take off somewhere else. The end result, Kissler said, is that if you look at the national average, our surges tend to build and die down more slowly than in the U.K.