COVID-19 live updates: City sees fourfold increase in pediatric hospitalizations

Eighteen states have an ICU capacity of 15% or less. Michigan in particular has been struggling through its latest COVID-19 surge for nearly three months.

Henry Ford Hospital in Detroit is seeing an increased number of ventilators in use and the "overwhelming majority" of patients on ventilators are unvaccinated, Dr. Jayna Gardner-Gray told ABC News.

Sarah Rauner, a chief nurse practitioner at Beaumont Health, told ABC News, "I have seen and witnessed things in the last two years that have forever changed me."

"I remember thinking to myself when we were going through the third surge, 'What are we going to do if there's a fourth?' And here we are in the middle of a fourth surge in the holidays. I am very concerned," she said. "We are burnt out. We are tired and we are disheartened. So much of what we see on a daily basis is preventable. However, we are still living this every day."

Rauner has one ask of all Americans: "Get your family vaccinated."

-ABC News' Arielle Mitropoulos

Maryland Gov. Larry Hogan said he tested positive for COVID-19 Monday morning.

Hogan, a cancer survivor, said he's vaccinated and booster and is "feeling fine."

-ABC News' Alisa Wiersema

The Israeli government on Monday passed a resolution adding the United States and Canada to its "red list," banning its citizens from traveling to those countries.

The ban, which would also stop visitors from those countries from entering Israel, is scheduled to go into effect Tuesday night at midnight local time, the prime minister's media advisor said in a statement following Monday's vote.

The Knesset Constitution, Justice and Law Committee has to approve the measure, which was recommended by the Health Ministry State Classification Committee.

Israeli citizens returning from "red list" countries must quarantine. Israelis are now barred from travelling to Belgium, Germany, Hungary, Italy, Morocco, Portugal, Switzerland and Turkey.

The omicron surge is so dangerous due to a combination of higher transmissibility and the variant's ability to make vaccinated people mildly sick from the disease, Dr. Ashish Jha, dean of the Brown University School of Public Health, said on "Good Morning America" Monday.

While there are still a lot of unknowns about omicron's severity, Jha said cases with this latest variant's surge are "doubling in numbers about every two to three days."

"That’s unlike anything we've seen," he said.

Jha said, "I do think lots of people are going to get [omicron]."

"It's an incredibly contagious variant. I think people should understand that the goal cannot be to avoid infection at all cost -- that's an unrealistic goal," he said. "The goal should be: prevent deaths and severe illness, which vaccines will do, [and] keep our hospitals from getting crushed, which again, vaccinations and testing can help with. This is very contagious. Lots of Americans will end up getting it. Let's just make sure that they don't get very sick from it. "

For people traveling over the holidays, Jha said airplanes are pretty safe, but he recommended wearing a high-quality mask because airports don't always have great ventilation.

Looking forward, Jha said, "I think we're going to be in much better shape next year."

The vaccines have already been in the U.S. for one year, Jha said, and he predicted the omicron surge will build more immunity.

"I am not saying COVID will be gone next winter. It will be around, but we should be able to get better and better at managing it," Jha said. "This winter is so much better than last year and I expect next winter will be so much better than this year."