Omicron represented 95% of sequenced Covid cases in the U.S. during the week ended New Year’s Day, while the once-dominant delta variant is now only 4.6% of sequenced cases, according to data from the Centers for Disease Control and Prevention.
The highly contagious omicron variant has overtaken delta in just a matter of weeks. At the beginning of December, omicron represented less than 1% of sequenced cases while delta made up 99% of them.
The U.S. reported a pandemic record of more than 1 million new infections on Monday, according to data compiled by Johns Hopkins University.
Omicron is driving up cases, at least in part, due to its ability to partially evade the immunity generated by vaccines and cause breakthrough infections in large numbers.
President Joe Biden said people who are fully vaccinated, particularly those who have received boosters, are highly protected against severe illness from omicron even if they are infected.
“You can still get Covid, but it’s highly unlikely, very unlikely, that you’ll become seriously ill,” Biden said Tuesday. “We’re seeing Covid-19 cases among vaccinated workplaces across America, including here at the White House, but if you’re vaccinated and boosted, you are highly protected.”