Many children returned to school on Monday from winter break and Minnesota Governor Tim Walz said he expects COVID-19 to spread quickly through schools because of the Omicron variant and said the already shortage of substitute teachers is challenging.

So far, no school district in Minnesota has moved students to fully distance learning from the surge of COVID-19 cases in the state, but several districts say they are "closely monitoring Omicron" as students returned to school after the break, WCCO Reported.

"They're right to be concerned," Walz told Minnesota Public Radio.

Some schools in the state even had their winter break early to try and slow the spread of COVID-19 and give their staff members a much-needed break.

The fast-spreading Omicron variant could put more strain on the staffing problems several schools already face. "We Already know that subs are in short supply. It is a challenge," Walz said.

School superintendents said they are "nervous about Omicron," Bob Indihar, executive director of the Minnesota Rural Education Association, told MPR.

Walz recommended the best way to avoid going back to distance learning and have schools remain open is to wear masks in public places and to get vaccinated and the booster shot if eligible and get tested.

"We're not helpless in this," he said. "We have the tools necessary to slow the spread of this."

Gov. Tim Walz, COVID-19 Spread in Schools
Minnesota Governor Tim Walz said he expects COVID-19 to rapidly spread through public schools in the next few weeks since students are back in class. Above, Senator Tina Smith and Minnesota Governor Tim Walz listen as Hennepin County District 4 Commissioner Angela Conley speaks on June 5, 2020, in Minneapolis, Minnesota. Stephen Maturen/Getty Images

Across the country, schools are adapting to the surge. Mask requirements are returning in some school districts that had dropped them. Some are ramping up virus testing among students and staff. And a few school systems are returning to remote learning.

Walz is back at work after he, his wife and his 15-year-old son tested positive and developed mild-to-moderate symptoms in late December. But because they were in quarantine, he said, their college-age daughter was not able to spend Christmas with them and stayed with relatives instead. He said they've all tested negative since then.

The governor said in a separate interview with WCCO Radio that Minnesota's efforts to ramp up testing will be complicated by President Joe Biden's announcement just before Christmas that the federal government will provide 500 million free at-home rapid test kits. He said that's a good move but said it's affecting Minnesota's existing supply chains. He said Minnesota is still in better shape than other states, but acknowledged that testing availability is tight, and he thanked people for being patient.

"Don't give up on this," Walz told WCCO. "Testing is the real key, along with the boosters, to helping stop the spread."

The Minnesota Department of Health on Monday reported 6,780 new cases and 48 new deaths to raise the state's totals to 1,028,986 cases, including re-infections, and 10,564 deaths since the pandemic reached the state in March 2020. More than 3.5 million Minnesotans age 5 or older have completed their vaccine series, or about 72 percent of the state's eligible population.

NYC Kids Returning
Many children returned to school on Monday from winter break and Minnesota Governor Tim Walz said he expects COVID-19 to spread quickly through schools because of the Omicron variant and said the already shortage of substitute teachers is challenging. Above, students with their parents arrive at Concourse Village Elementary School amid the recent spike in COVID-19 cases in the Bronx, New York on January 3, 2022. Photo by Timothy A. Clary/AFP via Getty Images