Studies show existing vaccines have been mostly effective against Delta variant

Most studies from around the world, including in Britain, Scotland, and Canada, are mostly showing that the vaccines currently in use in the United States have been effective against the Delta variant. But at least one epidemiological analysis from Israel found a decline in the Pfizer vaccine's ability to prevent infection — though it's still been highly effective at preventing serious illness. Natalie Dean, a biostatistician at Emory University, urged people, however, not to worry too much about any one study. "We just have to take everything together as little pieces of a puzzle, and not put too much weight on any one number."