LOS ANGELES, Feb. 20 (Xinhua) -- The highly transmissible Omicron subvariant XBB.1.5 now accounts for over 80 percent of new COVID-19 cases reported in the United States, according to the latest estimates of the U.S. Centers for Disease Control and Prevention (CDC).

XBB.1.5 is estimated to account for 80.2 percent of U.S. COVID-19 cases in the week ending Feb. 18, up from 73 percent in the week prior, according to the CDC.

BQ.1.1 remains the second most prevalent strain at 12.1 percent.

The CDC first started tracking XBB.1.5 in November last year, when it accounted for less than 1 percent of cases nationwide. Since then, the strain is spreading quickly in the United States.

Early study suggests XBB.1.5 has a couple of concerning mutations that suggest it is even more contagious than other strains.

While XBB.1.5 is spreading easier, scientists said it does not seem to cause more severe disease.