Americans who test positive for Covid-19 no longer need to stay in isolation for five days, US health officials announced on Friday.

The Centers for Disease Control and Prevention (CDC) changed its longstanding guidance, saying that people can return to work or regular activities if their symptoms are mild and improving and it has been a day since they have 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 recommendations 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.

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 are not testing to distinguish whether it is Covid-19, flu or something else, officials say.

This guidance may not be as stringent as it once was, but it 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 has been no recent change in the science of how long people with Covid-19 are likely to be 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.

The advice is now for people with symptoms to stay home until they are mild and improving and it has been a day since having had a fever.

There is no change to guidelines for nursing homes and healthcare 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 fresh outdoor air.