The US Centers for Disease Control and Prevention estimates that the Omicron XBB.1.5 subvariant represents nearly 90 percent of the country's new coronavirus cases.

The agency says the fast-spreading strain accounted for 89.6 percent of cases for the week through Saturday, an increase of about 4 percentage points from the previous figure of 85.4 percent.

The subvariant has been spreading through the United States since December.

Overall, however, the average daily number of new coronavirus infections in the US has been trending downward since January, and was at about 32,000 on Wednesday.

The daily average number of COVID-19 hospital admissions as of Tuesday was nearly 3,300, and the average death toll per day as of Wednesday was about 330. Both figures are also down from January.

The CDC classifies the infection situation in US communities using three levels -- low, medium or high. As of Thursday, about 82 percent of the communities had a low level while only about 2 percent were classified as high.