The coronavirus will hit millions of Americans in a "viral blizzard" within a few weeks as infections from the Omicron variant pile on top of Delta, an expert predicts.

Already, as the holiday season gets into full swing. Long lines for COVID-19 testing formed Thursday in metro areas, including New York, Boston and Miami.

The Delta variant remains a problem. And Omicron, with its , could strike millions more soon, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

"We're really just about to experience a viral blizzard," Osterholm told CNN's Erin Burnett on Thursday. "In the next three to eight weeks, we're going to see millions of Americans are going to be infected with this virus, and that will be overlaid on top of Delta, and we're not yet sure exactly how that's going to work out."

Omicron will cause a on the health care system as more workers will likely get sick, Osterholm said, even though from Omicron seem to be mild.

"What you have here right now is a potential perfect storm," Osterholm said. "I've been very concerned about the fact that we could easily see a quarter or a third of our health care workers quickly becoming cases themselves."

Other signs include:

 

  • New Orleans says it will require kids ages 5 to 11 be vaccinated before entering public schools, restaurants and other businesses.
  • Colleges and universities to online learning.
  • Sports leagues are due to players testing positive.
  • are cancelling performances.

 

CDC Director Dr. Rochelle Walensky said Friday the Omicron coronavirus variant is "increasing rapidly" and expected "to become the dominant strain in the United States as it has in other countries in the coming weeks."

Andy Slavitt, a former senior pandemic adviser to President Joe Biden, said that while tools such as vaccines are rather than during last winter's surge, "a very rough January" lies ahead due to Omicron.

"For the health care workers, the hospitals, for people who are sick, even sick with things other than COVID, that represents a real danger and a real threat," Slavitt told CNN's Don Lemon on Thursday.

Two indicators are up about 40 percent in the last month, according to data from Johns Hopkins University: the seven-day average of new cases topped 120,000; and the total number of hospitalizations stands at more than 68,000.

The seven-day average for deaths was 1,286 as of Thursday, an 8% increase from a month ago, the data show.

Getting vaccinated or boosted remains key as millions of Americans get ready for holiday travel.

Recent lab studies of blood taken from vaccinated people and exposed to Omicron showed the variant can evade some protection offered by two doses of Moderna's COVID-19 vaccine, but a booster dose restores much of that immunity, Wednesday. The Pfizer/BioNTech vaccine has shown .

On Thursday, the US Centers for Disease Control and Prevention changed its recommendations for Covid-19 vaccines to make clear that shots made by over Johnson & Johnson's vaccine.

The daily rate of vaccinations is up around 22% from a month prior, CDC data, with more than half being booster doses. At the current pace, it will take more than two months for at least half of adults to get a COVID-19 booster, according to a CNN analysis of CDC data.

Biden said Thursday that vaccinations and boosters are essential to keeping businesses and holiday gatherings safe.

"For the unvaccinated, we are looking at a winter of severe illness and death," he said. "But there's good news if you're vaccinated and you have your booster shot, you're protected from severe illness and death."

 

VACCINES STILL THE BEST WAY TO FIGHT COVID-19, OFFICIALS SAY

 

Even with the of the Omicron variant, former Obama White House health policy adviser Dr. Zeke Emanuel said the U.S. has tools to fight COVID-19, unlike during its onset.

"In March 2020, we didn't understand a lot about coronavirus. Second of all, we have vaccines now. We have the ability to change those vaccines. We're getting oral therapeutics. We have much better tests and test availability. None of that's perfect, but it's much better than it was in March 2020," Emanuel told CNN's Michael Smerconish on Thursday.

Continued research into to fight coronavirus is ongoing.

Merck's COVID-19 antiviral, molnupiravir, lowers the risk of hospitalization or death in high-risk unvaccinated adults by 30%, according to a statement issued after publication of its in the New England Journal of Medicine.

Among people who got the treatment, the risk of hospitalization and death was 6.8%, compared with 9.7% among people who got a placebo, the study said. There was one death in the treatment group, compared with nine deaths in the placebo group.

While successes are being found in some treatments pre- and post-infection, the rates of severe disease and death for those vaccinated continue to prove much lower even with vaccines' reduced effectiveness against certain variants.

"Given the increased risk related to the Delta and Omicron variant, it is important to increase uptake of primary vaccination and booster doses in all eligible populations," said Heather Scobie, a member of the CDC's Enhanced Surveillance Epidemiology Task Force COVID-19 Emergency Response.

 

PEOPLE CAN TRAVEL SAFELY WITH PRECAUTIONS, FAUCI SAYS

 

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said he is certain Omicron will become the dominant variant relatively soon.

"It has what we call a doubling time of about three days. And if you do the math on that, if you have just a couple of percentage of the isolates being Omicron, very soon it's going to be the dominant variant," he told ABC's "Good Morning America."

Yet as long as people get vaccinated and utilize precautions such as mask-wearing, Fauci said, lockdowns seen last year may not be needed and for a Christmas with other vaccinated people can be done safely.

"If you are vaccinated, and particularly if you are boosted, you're going to have to wear a mask on the plane anyway. That's a regulation. But be prudent and careful. When you go to the airport, particularly, that's an indoor congregate setting," Fauci told CNN's Wolf Blitzer.

"I believe that if people follow the recommendations of the CDC about indoor masking, take the advice of getting vaccinated and getting boosted, we should be fine for the holidays, and we should enjoy it with our family and our friends."

 

NEW ORLEANS TO REQUIRE VACCINATIONS FOR CHILDREN 5 TO 11

 

Beginning on January 3, children ages 5 to 11 will be required to provide proof of vaccination or a negative COVID-19 test before entering bars, restaurants and other businesses, New Orleans Mayor LaToya Cantrell announced in a press conference Thursday.

"Children ages 5-11 will be required to show proof of at least one vaccine dose. Beginning in February, the requirements will expand to two doses," she said.

The mandate will also be extended to children in New Orleans public schools starting Feb. 1.

Friday, Walensky said new evidence shows that "test-to-stay," which involves testing -- instead of quarantining -- students who may have been exposed to the virus at school, works to keep children in school safely, even if they have been exposed to the coronavirus.

"Test-to-stay is an encouraging public health practice to keep our children in school," Walensky said during a virtual White House briefing.

In the past few months, the CDC has collaborated with certain school districts to evaluate test-to-stay programs. Two of the communities that collaborated with the CDC are Lake County, Illinois, and Los Angeles County, California.