By Sheryl Gay Stolberg
The highly infectious Delta variant now accounts for an estimated 83 percent of new coronavirus cases in the United States — a “dramatic increase” from early July, when it crossed the 50 percent threshold to become the dominant variant in this country, the director of the Centers for Disease Control and Prevention said Tuesday.
In some regions, the percentage is even higher — particularly where vaccination rates are low, Dr. Rochelle Walensky, the C.D.C. director, said during a Senate health committee hearing. Two-dose vaccines have been shown to be effective against the Delta variant but questions have been raised about Johnson & Johnson’s single-dose regimen against Delta. While almost 60 percent of U.S. adults are fully vaccinated, less than half of the total U.S. population is.
She said the C.D.C. would update its website later Tuesday to reflect the new estimate of Delta cases, which the agency derives from gene sequencing of new coronavirus cases.