The highly transmissible Omicron variant has rapidly taken hold in the United States and now accounts for nearly three-quarters of new Covid-19 cases nationwide, according to the Centers for Disease Control and Prevention.
CDC estimates on Monday showed that Omicron accounted for an estimated 73.2 percent of U.S. cases surveilled between Dec. 12 and 18, with the Delta variant now accounting for 26.6 percent of cases. Between Dec. 5 and Dec 11, Omicron accounted for just 12.6 percent of U.S. cases, the agency estimated.
CDC Director Rochelle Walensky and other health officials last week said the expectation was the variant would become the dominant strain in the coming weeks. The White House has urged vaccinations and booster shots to combat the new variant, and President Joe Biden is expected to amplify that message during a speech on the state of the pandemic on Tuesday.