COVID-19 updates: 2 cases of omicron variant confirmed in Canada, officials say

New cases in the U.S. have jumped by more than 42% over the last four weeks, according to federal data.

These states as well as Washington, D.C., have seen at least a 10% uptick in daily cases over the last two weeks: Arkansas, Arizona, Colorado, Connecticut, Delaware, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Nebraska, New Jersey, New Hampshire, New Mexico, New York, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Tennessee, Texas, Vermont, Virginia and Wisconsin.

Michigan is currently experiencing its highest case average of the entire pandemic, according to federal data.

New York is now averaging its highest number of new cases since February.

More than 101 million Americans remain completely unvaccinated; 81 million of those people are over the age of 5 and thus eligible to be vaccinated, according to federal data.

-ABC News' Arielle Mitropoulos

Denver area hospitals are 95% full, Denver Health CEO Robin Wittenstein warned at a Tuesday news conference.

"Emergency rooms are routinely diverting patients because they simply don't have the capacity to take care of people who need help," Wittenstein said.

Eighty-three percent of hospitalized COVID-19 patients in Colorado are unvaccinated, said Bob McDonald, executive director of Denver's Department of Public Health and Environment.

"To suggest that the vaccines don't work... that's like suggesting seatbelts don't work," McDonald said.

Denver is implementing an indoor mask mandate unless businesses choose to require proof of vaccination.

-ABC News' Zachary Ferber

The Biden administration is asking a federal court to immediately reinstate a nationwide vaccine mandate for large businesses, arguing that the COVID-19 threat to unvaccinated workers is “ongoing and overwhelming.”

The mandate was supposed to go into effect Jan. 4. It was put on hold by another federal court that insisted the Labor Department’s Occupational Safety and Health Administration didn’t have the legal authority to impose such a requirement on private businesses.

In the new court filing to the 6th Circuit Court of Appeals, the Biden administration responded, “Congress charged OSHA with addressing grave dangers in the workplace, without any carve-out for viruses or dangers that also happen to exist outside the workplace."

“Delaying this standard would endanger many thousands of people and would likely cost many lives per day,” the lawyers wrote, adding that there was “extensive evidence of ‘workplace transmission.’”

-ABC News' Anne Flaherty

In September, unvaccinated people had a 5.8 times greater risk of testing positive for COVID-19 compared to vaccinated individuals, according to federal data pulled from 24 states and jurisdictions that has been published on the CDC website.

The unvaccinated are 14 times more likely to die from COVID-19, according to the CDC.

At Monday's White House COVID-19 briefing, CDC Director Rochelle Walensky said unvaccinated adults are nine times more likely to be hospitalized for the virus compared to vaccinated adults.

-ABC News' Arielle Mitropoulos