IE 11 is not supported. For an optimal experience visit our site on another browser.

Surge of delta variant causes growing concern

02:19

Cases of the highly contagious delta variant have doubled in the past two weeks, and Dr. Anthony Fauci is calling it the country’s “greatest threat” to defeating the coronavirus. Meanwhile, the White House is acknowledging the nation will not reach its 70 percent vaccination goal by July 4. NBC’s Tom Costello reports for TODAY.