(CNN) Covid-19 numbers keep soaring as travelers scatter back across the country after Christmas and Americans prepare for another holiday weekend.
The US is now averaging 198,404 new Covid-19 cases each day, according to Sunday data from Johns Hopkins University. That's 47% higher than a week ago and the highest such number since January 19.
"I think we're going to see half a million cases a day -- easy -- sometime over the next week to 10 days," CNN medical analyst Dr. Jonathan Reiner told CNN on Sunday.
About 71,000 Americans were hospitalized with Covid-19 as of Sunday, according to the US Department of Health and Human Services.
And an average of 1,408 Americans died from Covid-19 each day during the week ending Sunday, according to Johns Hopkins. That's a 17% increase from the prior week.
With the highly contagious Omicron variant, "We're certainly going to continue to see a surge (in cases) for a while," Dr. Anthony Fauci told CNN on Monday.
Looking ahead to New Year's Eve on Friday, small gatherings of fully vaccinated people will be safe, Fauci said. But he advised people to avoid large parties where they don't know the vaccination status of all guests.
"When you are talking about a New Year's Eve party where you have 30, 40, 50 people celebrating, you do not know the status of the vaccination, I would recommend strongly: Stay away from that this year," said Fauci, the director of the National Institute of Allergy and Infectious Diseases.
"There will be other years to do that. But not this year."
Pediatric Covid-19 hospitalizations keep rising, and they're nearing the record high set in early September.
Close to half of the Covid-19 tests being performed at Children's National Hospital in Washington, DC, are coming back positive, the hospital's infectious diseases chief told CNN on Monday.
It's an indication of just how quickly the new Omicron variant is spreading in the community, Dr. Roberta DeBiasi said. But so far, she said, the affected children are not any sicker than they were when previous variants circulated. There are just more of them.
"We have just seen a striking increase in ... both volume -- the number of tests that are positive -- and the percent of tests that are positive," DeBiasi told CNN in a telephone interview. "We've had up to almost half of the tests -- 48% of the tests -- to be positive and that's much, much higher than in prior waves where it was more on the order of, at the most, 17%. And if we look at the raw numbers of positives, on the last wave, we were impressed by like 80 positives a day and we've had almost 200 positives on some days. So it's very -- it's just very, very contagious."
But so far, there's no indication the Omicron variant is causing more severe disease, she said.
"We have not seen any difference in the severity," DeBiasi said.
The Ann & Robert H. Lurie Children's Hospital of Chicago reported the number of children testing positive is "incredibly high," Dr. Larry Kociolek, an attending physician and infectious disease specialist there, told CNN on Monday.
"Hospitalizations have quadrupled over our baseline over the past week," Kociolek told CNN. "Fortunately, a lot of these infections are either mild infections or incidental positives, since we screen all children before procedures and at the time of admission, and we've actually not seen any change in the number of children being admitted to the ICU."
Half of the hospitalizations were in children younger than 5, Kociolek said. Children in that age group are not yet eligible to be vaccinated.
"I think we're definitely seeing the impact of vaccines in kids older than 5. The kids that are hospitalized are essentially all unvaccinated," Kociolek said.
For the week ending December 24, an average of 262 children were hospitalized with Covid-19 on any given day, according to data from the DHHS and the US Centers for Disease Control and Prevention.
That's almost a 35% jump from the previous week. The record daily average of child Covid-19 hospitalizations was 342 per day in late August and early September.
About 75,000 children, from babies up to age 17, have been hospitalized with Covid-19 since August 2020, according to CDC data.
New York state broke a single-day record for new Covid-19 cases, with 49,708 new Covid-19 cases reported on Christmas Eve, according to data released on Sunday by Gov. Kathy Hochul's office.
"As we come home from holiday gatherings, it is as important as ever to take precautions to limit the spread of COVID-19 this season," Hochul said in a statement. "The vaccine is the best tool we have to keep ourselves and our loved ones safe as we head into the new year."
The average number of daily new Covid-19 cases in New York City skyrocketed 644% in the past two weeks to 19,268, according to The New York Times.
The highly contagious Omicron variant was a factor in New York Mayor Bill de Blasio's decision to implement a vaccine mandate for private sector employees, effective Monday. The updated rules require workers to have at least one dose of Covid-19 vaccine by Monday and don't allow employees to opt out through regular testing.
Children ages 5 to 11 in New York are now also required to show proof of at least one shot before being allowed into indoor dining, fitness or entertainment venues. And adults must show proof of two vaccinations for those areas.
The private-sector requirements align with those already in place for the city's public sector employees and similar restrictions in major cities around the country.
"We need to take very bold action," de Blasio said. "We're seeing restrictions starting to come back. We're seeing shutdowns," he said. "We cannot let those restrictions come back. We cannot have shutdowns in New York."
The city is still planning a "scaled back" New Year's Eve celebration.
As more hospitals get overwhelmed, the CDC has issued new guidance that will allow some health care workers who get Covid-19 to return to work more quickly. Medical workers who test positive but don't have symptoms can go back to work in seven days if they test negative within 48 hours of their return to work.
That "isolation time can be cut further if there are staffing shortages," the CDC said Thursday.
But the new guidelines are only for health care workers. On Monday, the CDC also updated its recommended isolation and quarantine period for the general population.
The CDC shortened the recommended time for isolation from 10 days for people with Covid-19 to five days, if asymptomatic, followed by five days of wearing a mask when around others.
"The change is motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness, generally in the 1-2 days prior to onset of symptoms and the 2-3 days after," the CDC said in a statement announcing the updated guidelines.
The CDC also updated its recommended quarantine period for those exposed to Covid-19.
For those who are unvaccinated, have not had a second mRNA dose in more than six months or have not had a booster shot, the CDC recommends quarantining for five days followed by strict mask use for an additional five days.
People who have received their booster shot do not need to quarantine if they are exposed to Covid-19, but they should wear a mask for 10 days after exposure, the statement read.
The CDC said it "continues to evaluate isolation and quarantine recommendations for the broader population as we learn about the Omicron variant and will update the public as appropriate."
The emergency guidance for health care workers was made because of concerns about the Omicron variant and potential staff shortages, the CDC said.
About 75% of all ICU beds in the country were in use and about 21% were occupied by Covid-19 patients, according to Sunday data from the US Department of Health and Human Services.
At Tufts Medical Center in Boston, the new CDC guidance was welcome news.
"We have, as of this morning, 115 staff members out ill with Covid who have tested positive," Chief Operating Officer Diana Richardson said Monday.
"But some of them are not as acutely ill. In fact, some of them are asymptomatic completely -- we have a very vaccinated population. So it will help us to bring those individuals back into the workforce."
Thousands of flights were canceled over the holiday weekend -- partly due to winter weather but largely due to reduced airline staffing as employees called out sick.
More than 2,000 flights were canceled Monday, according to the flight tracking website FlightAware. That's on top of roughly 1,200 Sunday flights that were canceled.
And at least four ocean cruise ships were turned away from ports or prohibited from letting passengers disembark this past week because of Covid-19 cases on board.
Sporting events have also been postponed or canceled because of increased spread of Covid-19. At least five college football bowl games have been affected, including two games called off over the weekend. Pro basketball and hockey also have been slowed by the virus.
The best way to protect against severe illness is to get vaccinated and boosted, Fauci said.
"Boosters are always good for any variant, but particularly for Omicron," he said.
"If you are vaccinated and not yet boosted, and your time comes for getting boosted, please get boosted. It's going to make all the difference to prevent you from getting severe disease."