CHICAGO (CBS) – Illinois reported 18,942 new cases of COVID-19 on Thursday, the most infections ever reported in a single day during the pandemic.

Illinois is averaging 12,573 new cases of COVID-19 per day over the past week, more than double the average of 6,119 cases per day at the start of December.

READ MORE: Chicago Has 'Formally Passed The Omicron Peak' As New COVID-19 Infections Decline, Hospitalizations Level Off, Top Doc Says

Testing also has skyrocketed this month, with Illinois averaging 223,281 tests per day over the past week, up 123% since the start of December.

The latest surge in cases comes as the Omicron variant has become the dominant strain of the virus in the U.S., accounting for more than 73% of new cases in the nation last week.

READ MORE: No Changes To Chicago Travel Advisory; Every State Remains On The List For 3rd Week In A Row

Omicron has proven to be the most contagious variant so far, as much as three times more contagious than the Delta variant, which itself is more contagious than the original strain of COVID-19.

Deaths and hospitalizations from COVID-19 also are on the rise in Illinois.

As of Wednesday night, a total of 4,271 people were hospitalized with COVID-19 in Illinois, a 68% increase from the start of December.

MORE NEWS: 15-Year-Old Killed, Five Other Juveniles Wounded In Trio Of Shootings In Chicago On Tuesday

Illinois is averaging 53 deaths from COVID-19 per day over the past week, up more than 150% from the start of December.

CBS 2 Chicago Staff