The omicron variant accounts for 95% of all new COVID-19 cases in the U.S., according to data from the Centers for Disease Control and Prevention released Tuesday.

In early December, the highly transmissible variant made up 0.6% of new infections.

Meanwhile, the delta variant -- responsible for the summer surge -- makes up 4.6% of new cases, the CDC said.

The data also showed the omicron variant is dominant in all regions of the country. In the New York-New Jersey region and in the Southeast, the variant is linked to 98% of new infections.

-ABC News' Arielle Mitropoulos

The United Kingdom recorded more than 200,000 cases of COVID-19, according to the UK Health Security Agency.

The 218,724 new infections is the highest figure ever reported in a single day and an increase of nearly 60% from the number of cases reported on the same day last week.

However, there has been a backlog of data due to the holiday weekend so the number includes four days of data from Northern Ireland and two days of data from Wales, the UKHSA said.

-ABC News' Mike Trew

Sen. Rob Portman, R-Ohio, tested positive for COVID-19 last night, according to a press release.

Portman took an at-home COVID test which came back positive. The senator said he is asymptomatic and feels fine.

"I have been in contact with the Attending Physician and my personal doctor. I am following their medical advice and following CDC guidelines and isolating for the recommended five days," Portman said in the statement.

He will be working remotely this week, but will not be able to be in Washington, D.C., for votes.

Sweden's King Carl XVI Gustaf and Queen Silvia tested positive for COVID-19 last night, according to a palace statement.

Both are fully vaccinated and have received a third booster shot.

The king and queen said they have mild symptoms and are feeling well, in the statement.

They are isolating at home and contact tracing is ongoing.

Chicago Public Schools canceled its Wednesday classes after the Chicago Teachers Union voted against in-person learning amid a wave of COVID-19 cases.

All classes, both in-person and virtual, and all after-school activities have been cancelled.

"I understand your frustration and deeply regret this interruption to your child's learning," said Pedro Martinez, chief executive of the schools. "We want out children back in their classrooms as soon as possible and will continue working with the CTU to reach an agreement that addressed their concerns and that is in the best interest of all in our CPS community, especially our children."  

About 88% of the union's leadership and 73% of members voted on Tuesday to return to remote education, the union said in a statement.  

"To the parents and guardians of this city, we want you to know that when you put your children in our care we put their well-being and safety first," the union said in a statement. "We fight for your children like they are our own, because they are. As this pandemic continues, we will do everything in our power to ensure that our classrooms are the safest and healthiest places for your children to learn, thrive and grow."

Teachers were being locked out of their Google Classrooms, the union said on Twitter.