US health officials on Monday reduced COVID-19 isolation recommendations from 10 to five days, and similarly shortened the time that close contacts need to quarantine.

Centers for Disease Control and Prevention officials said the guidance is in keeping with growing evidence that people with the coronavirus are most infectious in the two days before and three days after symptoms develop. 

Last week, the agency cut isolation restrictions for healthcare workers who catch the coronavirus from 10 to seven days if they test negative and don't have symptoms. And the agency said isolation time could be cut to five days, or even fewer, if there are severe staffing shortages. 

Now, the CDC is changing the isolation and quarantine guidelines for the general public who are not experiencing symptoms. People with symptoms during isolation, or who develop symptoms during quarantine, are encouraged to stay home.

The new CDC guidance is not a mandate; it's a recommendation to employers and state and local officials.

"Not all of those cases are going to be severe. In fact, many are going to be asymptomatic," CDC Director Rochelle Walensky said Monday. "We want to make sure there is a mechanism by which we can safely continue to keep society functioning while following the science."

As the highly contagious Omicron coronavirus variant continues to spread across the US, positive cases are being reported at record levels in parts of the US, surpassing last winter's peak.

The seven-day average of new daily cases in the US was more than 203,000 on Sunday, according to The Washington Post, a level not seen since Jan 19. In the week ending Sunday, the country reported 1.39 million cases — nearly 200,000 per day. This number is 47 percent higher than a week ago, and 65 percent higher than two weeks ago, according to USA Today.

New case records were set in Delaware, Maryland, New Jersey, New York and Puerto Rico. 

New York state recorded more than 49,000 new cases Sunday, the highest number it has reported during the pandemic, according to data released on Sunday by Governor 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."

Washington DC has more than 1,300 cases per day, far surpassing last winter's peak of 322. Cases in Maryland have risen sharply with nearly 6,200 cases per day, almost double their highest point last winter, according to the Post.

Coronavirus cases in Los Angeles County have nearly tripled in the last week, reaching 9,998 new cases for its 10 million residents. 

Some areas also have reported an increase in hospitalizations. Washington DC reported 77 percent more COVID-19 hospitalizations, and 42 percent more COVID-19 patients are in intensive-care beds, compared with the number a week earlier.

Florida's hospital admissions are up 64 percent. Hawaii's are up 44 percent, according to US Department of Health and Human Services (HHS) data reported Sunday.

The hospitalization wave is moving unevenly across the country. Nationwide, hospitalizations and deaths from COVID-19 have not risen as sharply — nearly 71,000 Americans are hospitalized with COVID-19, 8 percent higher than the previous week but still below previous peaks, according to The New York Times.

Eighty percent of people hospitalized with COVID-19 are not fully vaccinated, HHS reported.

Pediatric hospitalizations are up 395 percent in New York City since the week ending Dec 11, from 22 to 109 the week ending Dec 23. 

Statewide pediatric hospitalizations jumped from 70 to 184, according to New York state Health Commissioner Dr Mary Bassett, who announced the data Monday.

Bassett said vaccination rates among 5-to-11-year-olds were "disappointingly low". Only 16.4 percent of children in that age group across New York are fully vaccinated, which is up from 11 percent two weeks ago, and 27.3 percent of them have received one dose, he said. 

The average number of daily new coronavirus cases in New York City skyrocketed 644 percent in the past two weeks, according to The New York Times.

New York City on Monday reported 17,334 virus cases, Mayor Bill de Blasio said, and he said he believed the positive case number "is going to peak really soon".

According to the city government website, 82.8 percent of adults in New York are fully vaccinated.

De Blasio said that citywide, there were 296 COVID-19 hospitalizations Monday, and that number had gone up intensely, as did the confirmed positivity level — 7.96 percent. 

However, he added that the city's hospitals are "doing remarkably well. We have real challenges, but what's striking is how different the Omicron experience is than even last winter, let alone the spring of 2020".

New York City's latest vaccine mandate started Monday in which private employers must require COVID-19 vaccinations for their workers on premises.

The updated rules require workers to have at least one dose of the COVID-19 vaccine by Monday and they cannot opt out through regular testing. 

The order affects an estimated 184,000 businesses. Those that do not comply could face fines starting at $1,000. 

It's still unclear whether Mayor-elect Eric Adams, who takes office on Jan 1, will keep de Blasio's COVID policies in place.

"The mayor-elect will make announcements on his administration's Covid policy this week," said his spokesman, Evan Thies, in a text message Monday, The New York Times reported.

Beginning Monday, children ages 5 to 11 in the city also are required to show proof of at least one shot before being allowed into indoor dining, fitness or entertainment venues; anyone age 12 or older must show proof of two vaccinations for those areas.

The Associated Press contributed to this story.