Originally Published: 11 AUG 22 15:00 ET

Updated: 11 AUG 22 16:31 ET

By Brenda Goodman and Elizabeth Cohen, CNN

(CNN) -- The US Centers for Disease Control and Prevention says the nation should move away from restrictive measures such as quarantines and social distancing and focus on reducing severe disease from Covid-19.

In new guidelines released Thursday, the agency no longer recommends staying at least 6 feet away from other people to reduce the risk of exposure -- a shift from guidance that had been in place since the early days of the pandemic.

The shift is a sign of how much has changed since the beginning of the pandemic more than two years ago. Nearly the entire US population has at least some immunity through vaccination, previous infection or, in some cases, both.

"The current conditions of this pandemic are very different from those of the last two years," Greta Massetti, who leads the Field Epidemiology and Prevention Branch at the CDC, said Thursday.

"High levels of population immunity due to vaccination and previous infection and the many available tools to protect the general population, and protect people at higher risk, allow us to focus on protecting people from serious illness from Covid-19."

The new CDC guidelines say contact tracing, another hallmark during the pandemic, should be limited to hospitals and certain high-risk group-living situations such as nursing homes, and the guidelines de-emphasize the use of regular testing to screen for Covid-19, except in certain high-risk settings like nursing homes and prisons.

The new guidance also does not advise quarantining people who've been exposed to Covid-19 but are not infected.

But the guidance does keep some measures the same. It encourages testing for people with symptoms and their close contacts. It also says people who test positive should stay home for at least five days and wear a mask around others for 10 days. It also continues to recommend that people wear masks indoors in about half the country.

The new guidelines also tailor advice on isolation for people who became very sick from Covid-19. People with moderate symptoms -- such as shortness of breath -- and those who were hospitalized should stay home for at least 10 days. People with compromised immune systems should now talk to their doctor about ending their isolation after an infection.

There's new advice on what to do if your Covid-19 symptoms rebound, too. If you end isolation and your Covid-19 symptoms get worse, you should start isolation over again and see your doctor.

Trying to meet people where they are

The changes are an acknowledgment that SARS-CoV-2 may be with us for the long haul. They aim to help people live their lives around Covid-19 with minimal disruptions to work and school. They are also more risk-based, advising people who are at higher risk for severe illness to take more personal precautions than others.

"I think they just overall come into alignment with what people are doing anyway," says Dr. Peter Chin-Hong, an infectious disease specialist at the University of California at San Francisco.

Chin-Hong thinks some states, like California, will continue to go beyond the CDC's guidance in their own recommendations, but by and large, he thinks these reflect the prevailing attitudes toward the pandemic. He sees it as a move by the CDC to try to regain the public's trust.

A recent survey from the Annenberg Public Policy Center shows that most Americans (54%) are no longer masking indoors, and about 4 in 10 say they've fully returned to their pre-pandemic routines -- up from 16% in January.

"What the CDC is, in my opinion, trying to do, they are trying to still be relevant, and maybe when they say something, people will listen to them instead of being completely 180 degrees away from what behavior is anyway," Chin-Hong said.

Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, agrees that the new guidance shows that the CDC is trying to meet people where they are.

"I think that this is a point where you actually have to sort of get real and start giving people tools they can use to do something or not. Because otherwise, people will just will not take you seriously," Hanage said.

Other experts, however, feel that the new guidelines don't go far enough to correct scientific missteps in previous guidance.

"This revision does not go anywhere near enough to correct the problems of flawed recommendations and lack of evidence," said Dr. Eric Topol, a cardiologist at Scripps Research Institute in La Jolla, California, said in an email to CNN. Topol has been critical of the CDC for months, saying it wasn't strict enough with its isolation policies for people with Covid.

Latest advice to stay safe from Covid

The CDC recommends that Covid-19 prevention practices continue to depend on a person's risk of becoming severely ill and on its Covid-19 community levels. Community levels reflect cases in a community as well as hospitalization rates and hospital capacity.

When the Covid community level is high -- as it currently is in 41% of counties -- the CDC continues to recommend that everyone wear high-quality masks indoors. High-risk people should also wear quality masks when the community level is medium, as it now is in 39% of counties.

The agency also puts more emphasis on improving ventilation. Aerosol scientists have long complained that the 6-foot social distancing guidance was arbitrary and unhelpful because the virus that causes Covid-19 can float through the air for greater distances.

The CDC continues to stress the use of vaccines and therapeutics to reduce "medically significant illness" in Covid-19. For the general population, the agency noted that being vaccinated and boosted is highly protective against severe illness and death. It urges everyone to stay up to date on their shots.

In addition to vaccination, the CDC urges additional measures for people with suppressed immune function, including the use of Evusheld, a kind of passive immunity that's given before a person gets sick. It's especially helpful for people who can't mount an immune response, and experts say it has been underutilized in this country.

The agency also stresses the use of antiviral medications in people who catch Covid-19 and are at higher risk for severe outcomes. This group includes people who are older or unvaccinated or those who have certain medical conditions that put them at higher risk. Conditions that increase risk include overweight and obesity, pregnancy, smoking, diabetes, cancer, heart disease and mental health conditions, including depression.

"These recent changes recognize the importance of protecting those most at risk of severe illness, while also standardizing some basic good public health hygiene for the long-term for those less at risk," said Lori Tremmel Freeman, CEO of the National Association of County and City Health Officials.

"It's important that we make it as easy as possible for people to continue to protect themselves and others around them as we live with Covid," Freeman said in an email to CNN.

Covid guidance for schools

Some of the changes in the guidelines will apply to schools.

The agency removed the recommendation that kids in different classrooms avoid mixing, a practice known as cohorting. It also removed advice that kids who are contacts of someone who tested positive for Covid-19 take regular tests -- and test negative -- to remain in the classroom, which was known as test-to-stay.

Some educators said they didn't expect the updated CDC guidelines to change much, at least for this school year.

"We welcome clear, concise and actionable guidance from the CDC. Specific to this latest round, we don't expect it to be particularly disrupting or impactful in schools," said Noelle Ellerson Ng, associate executive director of advocacy and governance at AASA, The School Superintendents Association.

Many districts have finalized their opening plans and mitigation strategies and are sticking to what worked the prior school year to keep kids in schools learning.

Randi Weingarten, president of the American Federation of Teachers, one of the nation's largest teachers unions, said the new guidelines were welcome news for schools.

"COVID-19 and other viruses are still with us, but with multiple prevention and treatment options available, now is not the time for new mandates. Instead, let's ensure these tools are available and accessible: vaccines, testing and masks (and no stigma for those who mask)," Weingarten wrote in an email to CNN.