■U.S. health officials have reduced the isolation period for COVID-19 from five days.

■CDC changed its guidelines, allowing those with mild symptoms to return to work.

■There is no change to guidelines for nursing homes and health care facilities.

NEW YORK — Americans who test positive for COVID-19 no longer need to stay in isolation for five days, U.S. health officials announced Friday.

The Centers for Disease Control and Prevention changed its longstanding guidance, saying that people can return to work or regular activities if their symptoms are mild and improving and it’s been a day since they’ve had a fever.

The change comes at a time when COVID-19 is no longer the public health menace it once was. It dropped from being the nation’s third leading cause of death early in the pandemic to 10th last year.

Most people have some degree of immunity to the coronavirus from past vaccinations or from infections. And many people are not following the five-day isolation guidance anyway, some experts say.

“Our goal here is to continue to protect those at risk for severe illness while also reassuring folks that these recommendation are simple, clear, easy to understand, and can be followed,” said Dr. Mandy Cohen, the CDC’s director,

However, some experts worry that the change may increase the risk of infection for those people who are more vulnerable to developing severe illness.

Reasons for the Change

COVID-19 is not causing as many hospitalizations and deaths as it did in the first years of the pandemic. The change is an effort to streamline recommendations so they are similar to longstanding recommendations for flu and other respiratory viruses. Many people with a runny nose, cough or other symptoms aren’t testing to distinguish whether it’s COVID-19, flu, or something else, officials say.

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This may not be as stringent, but also emphasizes that all people with respiratory symptoms should stay home while they are sick, said Dr. David Margolius, the head of Cleveland’s health department.

There’s been no recent change in the science of how long people with COVID-19 are likely contagious, said Jennifer Nuzzo, director of the Pandemic Center at Brown University’s School of Public Health.

“What has changed is how much COVID is harming us as a population,” Nuzzo said.

New Guidelines

If you have symptoms, stay home until your symptoms are mild and improving and it’s been a day since you’ve had a fever. But then you can remain cautious by wearing a mask and keeping a distance from others.

There is no change to guidelines for nursing homes and health care facilities, however.

The agency is emphasizing that people should still try to prevent infections in the first place, by getting vaccinated, washing their hands, and taking steps to bring in more outdoor fresh air.

Opposition to the Change

Yes, and even some who understand the rationale for the change have concerns.

“My biggest worry in all of this is that employers will take this change in guidance to require employees to come back to work … before they are ready to, before they feel well enough, and before they are not likely to pose harm to their co-workers,” Nuzzo said.

Previous Changes in Isolation Guidelines

No. The CDC originally advised 10 days of isolation, but in late 2021 cut it to five days for Americans who catch the coronavirus and have no symptoms or only brief illnesses. Under that guidance, isolation only ends if a person has been fever-free for at least 24 hours without the use of fever-reducing medications and if other symptoms are resolving.

At the time, agency officials said the changes were in keeping with evidence that people with the coronavirus were most infectious in the two days before and three days after symptoms develop.