By Hanna Park
(WASHINGTON) The delta coronavirus variant accounts for about 10% of new cases in the U.S., the Centers for Disease Control and Prevention announced Tuesday.
The delta variant – which was first detected in India – was declared a "variant of concern," a classification given when there is increased evidence of transmissibility, severity or reduced effectiveness of vaccines or treatments, NBC News reports.
The change in designation "is based on mounting evidence that the Delta variant spreads more easily and causes more severe cases when compared to other variants, including B.1.1.7 (Alpha)," the CDC said in a statement.
In April, the alpha variant first detected in the United Kingdom reportedly became the dominant strain in the U.S.
The delta variant accounts for 9.9% of cases in the U.S., according to data for the two-week period ending June 5, per the CDC. For the two-week period ending May 22, that figure was at 2.7%.
"Because [delta] has an advantage in terms of transmissibility, it takes over," Dr. Wafaa El-Sadr, director of ICAP at Columbia University and professor of epidemiology, told NBC. "It's just a matter of time."
The vaccines authorized for use in the U.S. are effective against the delta variant, as well as the other variants. The Moderna and Pfizer-BioNTech vaccines require two doses, while the Johnson & Johnson vaccine requires one shot.
Over 54% of U.S. adults have been fully vaccinated as of Tuesday, and nearly 65% had received at least one dose.