When the Covid public health emergency expired in May, health officials in Oregon decided it was also time to pull back on the recommendation that its residents, including schoolchildren, isolate for five days after testing positive for the virus.
Instead, the Oregon Health Authority suggested that people with Covid stay home only until they've gone without spiking a fever for 24 hours and are generally feeling better.
The move was a break from guidance from the Centers for Disease Control and Prevention, which continues to recommend that people stay home for a five-day period and stay away from household members.
"Covid has not gone away," said Dr. Dean Sidelinger, state epidemiologist for the Oregon Health Authority, "but based on what we're seeing in Oregon, all indications are that we're moving in the right direction."
Covid-related hospitalizations are down in Oregon, and wastewater surveillance indicates spread is either holding steady or decreasing.
What's more, "our level of immunity is high," Sidelinger said. "That made us feel comfortable moving to a symptom-based recommendation for isolation."
National Covid trends are similar, according to CDC tracking. The agency won't say whether it plans to update its isolation guidance any time soon.
"CDC is continuously reviewing its guidance for needed updates and recognizes that states may choose to implement CDC recommendations based on the needs of their own communities," Kathleen Conley, a spokesperson for the agency, wrote in an email.
With much of the Covid testing done in private or not at all anymore, it is likely that many Americans don't bother with isolation anyway.
So, who is still following the CDC guidance? Schools, nursing homes and businesses.
How long should you actually isolate?
The current recommendation to isolate for five days is a "hangover" from when the CDC moved from a 10-day isolation recommendation to five days in late 2022, just as the first wave of omicron was taking hold in the U.S., said Harvard University epidemiologist Bill Hanage.
"It was not a reflection of evidence-based" science, he said. "It was there to stop everything from falling apart."
At that time, a large chunk of the population was testing positive all at once because of the highly contagious variant. Recommending that everyone stay home — and out of work — for 10 days would have brought the country to a halt once again, so the five-day plan was put in place.
"If you look at the safety of the public, and the need to have society not disrupted, this was a good choice," Dr. Anthony Fauci, former scientific adviser to the Biden administration, said at the time about the isolation recommendation.
There was also evidence that people are most contagious during those first five days of infection. That remains the most reliable scientific data, experts say.
"We know that most people with Covid-19 shed enough virus that they are likely still contagious for at least five days," Jennifer Nuzzo, director of the Pandemic Center at Brown University School of Public Health, wrote in an email.
"The ending of the public health emergency declaration doesn't change biology," Nuzzo wrote. "I don't see a biological reason to end the five-day isolation period."
What we know about being contagious
People with the flu are most contagious the first three or four days after the illness begins, according to the CDC. People who test positive for influenza are advised to stay home "until at least 24 hours after their fever is gone" without the use of fever-reducing medicines, such as Tylenol.
A common cold virus is most contagious within the first few days but can continue to spread for up to two weeks, according to Johns Hopkins All Children's Hospital research.
Like other viruses, people with Covid have varying degrees of sickness.
A set number of days to isolate is "dumb if you think about it from a medical perspective," said Dr. Peter Chin-Hong, an infectious diseases specialist at the University of California, San Francisco.
"If you're feeling fine the entire five days and have absolutely no symptoms, staying at home by yourself is not the same as somebody who's had symptoms and then after five days, they're going out and coughing on everyone," Chin-Hong said. "The symptoms approach makes more sense, not just for Covid, but for lots of other infectious diseases that people don't normally isolate for."
It's not appropriate to compare Covid to the flu, Nuzzo insisted.
"Flu isn't still killing hundreds of Americans per day, but Covid-19 is," she said.
Chin-Hong agreed, saying that to have this many deaths from Covid in 2023 is a "tragedy." It's why the isolation question is so complicated.
'If you're sick, stay away from people'
While Chin-Hong believes that the changes the Oregon Health Authority made are "reasonable," he said it's not time for a symptom-based approach at a national level just yet.
Oregon is the only state so far to relax its isolation guidance, said Dr. Anne Zink, president of the Association for State and Territorial Health Officials.
Some state health officials said they feel more comfortable keeping the five-day isolation guidance, with the caveat that "no one protocol, no one CDC recommendation, no one state recommendation is going to work for every situation," said Zink, who is also chief medical officer of the Alaska Department of Health.
For example, health authorities in Alaska have kept the recommendation to isolate for five days after a positive Covid test. But they also work with local jurisdictions and businesses to assess the risks and benefits of that guidance, Zink said.
"What's going to work in Utqiagvik, Alaska, versus out in the Bering Sea versus Anchorage is going to be very different," Zink said. "How the people in our state live and work and play are so different, so we point them to the CDC guidance and then individually walk them through" whether the isolation period is the right approach.
On an individual level, common sense should rule, Hanage said. If you're sick, stay away from people most at risk for severe complications, such as elderly relatives.
"You wouldn't want to give them something that would make them badly ill — whether it's Covid, flu or even food poisoning," he said.
CORRECTION (June 12, 2023, 11:15 a.m. ET): A previous version of this article misstated Jennifer Nuzzo’s title and employer. She is director of the Pandemic Center at Brown University School of Public Health; she is not senior scholar at the Johns Hopkins Center for Health Security.