Michmutters

More than 2½ years into the pandemic, and with a highly contagious version of the virus circulating, the CDC guidelines for what to do when falling ill — and when to return to public life — continue to stoke as much confusion as clarity. That’s a reflection of the changing nature of the virus, the inherent unpredictability of an infection, and the demands and expectations of work and home life.

With new research showing that people are often infectious for more than five days, the CDC guidance has drawn criticism from some infectious-disease experts. The Biden protocol strikes many of them as the right way to go — because it’s empirical evidence that a person isn’t shedding virus.

The CDC does not explicitly recommend a negative test to patients who want to resume activities. It describes such a test, which offers a direct if imperfect measure of contagiousness, as optional. The guidance states that a patient should isolate for at least five days. (Day 1 is the day after your symptoms manifest or your test was collected.) Patients who end isolation should continue to wear a well-fitting mask around others at home or in public through Day 10.

“Given that a substantial portion of people do have a rapid positive test after 5 days, I think an updated recommendation should include people having a negative rapid test before coming out of isolation for COVID,” said Tom Inglesby, director of the Johns Hopkins Center for Health Security, who was the Biden administration’s senior adviser on testing from December until April.

Rapid tests are widely available, and “there is new science and practical experience with this virus since December when isolation guidance was issued,” Inglesby said in an email.

People who are being required to go back to their workplaces after five days of being sick with covid even if they still have a positive test result “shouldn’t do that,” Inglesby said. “It’s exposing others in the work environment to the risk of COVID spread. CDC guidance on that would be valuable.”

Biden has used his brief about the coronavirus as a sign that the administration is on top of the pandemic and has made the right moves by relying on vaccinations, testing and new antiviral drugs to lower the death rate. But across the country, hundreds of thousands of people a day are getting infected with the omicron subvariant BA.5 — the exact number is impossible to know — and they have a common, urgent need to know when they are no longer contagious.

The CDC’s guidance has been under internal review in recent months. A revamped set of recommendations is expected to be rolled out in coming weeks, according to three administration officials and advisers who spoke on the condition of anonymity to describe sensitive internal discussions. A draft of the updated guidance at the moment does not include a requirement to test negative before exiting isolation, they said.

The existing CDC guidance says patients can end isolation five days after their first day of symptoms, so long as their symptoms have improved and they have been fever-free for at least 24 hours without fever-reducing medication. The CDC encourages people who become very sick or have weakened immune systems to isolate for 10 days.

That leaves a negative test result as optional.

Robert Wachter, chair of medicine at the University of California at San Francisco, said people can easily misconstrue the CDC five-day guidance as a personal assurance of no longer being contagious.

“Unfortunately, people hear the ‘five days’ and think, ‘Oh, it must be that I’m not infectious,’ ” Wachter said. “That’s just wrong.”

A recent study in the New England Journal of Medicine looked at how long people could shed viruses that could be cultured in a laboratory — the best test of infectiousness. The result: People shed such virus for eight days, on average, before testing negative.

The CDC guidance “doesn’t make sense,” said Andrew Noymer, an epidemiologist at the University of California at Irvine. “They’re telling people to go back to work while they’re still contagious, essentially.”

Wachter suggests that people test negative before heading out in public.

“The antigen test turns out to be an awfully good ‘are you infectious’ test,” Wachter said. “If they’re still testing positive on Day 6, 7 or 8, I don’t want them hugging me in a room without a mask on.”

Officials familiar with the crafting of covid policy say the administration has to take into account human behavior — what people can, and will, do in their daily lives to limit virus transmission.

The administration’s decision not to push strongly for a negative test before ending isolation reflects an awareness that not everyone has access to tests or can extend time away from work, school, caregiving or other duties.

When CDC Director Rochelle Walensky was asked recently why the agency doesn’t recommend that all Americans use successive negative tests to exit isolation, as Biden did, she said the president was in a special category.

The president received multiple rapid tests because he was being monitored for a Paxlovid “rebound” infection, which can occur days after initially testing negative. Biden tested negative Thursday and Friday mornings before a positive result Saturday morning indicated the rebound, sending him back into isolation, White House physician Kevin C. O’Connor said in a letter. “Unsurprisingly,” Biden tested positive again Sunday, O’Connor said.

Walensky said during a Washington Post Live interview that “I think we can all agree that the president’s protocols likely go above and beyond and have the resources to go above and beyond what every American is able and has the capacity to do.”

“As we put forward our CDC guidance, we have to do so, so that they are relevant, feasible, followable by Americans,” she said, noting that some communities have fewer resources and greater work constraints.

She also noted that the guidance gives people the option to get a rapid test before ending isolation.

The five-day isolation period reflects an approximation of when people are most likely to be infectious. But these are averages, covering broad populations.

A positive result from a rapid antigen test, often called an at-home test, is the best indicator of how much virus is present and how likely you are to infect someone, said Michael Mina, a former Harvard University infectious-disease epidemiologist and immunologist who is an expert on rapid tests. Rapid antigen tests look for specific viral proteins to detect infection. Mina is chief science officer at a telehealth company that uses rapid testing, including for covid, to link patients to care.

“If you still have enough virus to see it on a rapid test, you know that you’re still infectious,” Mina said.

The California Department of Public Health, for example, requires a negative test on the fifth day after first testing positive, or later, to leave isolation.

Policymakers could help patients by releasing “clearer guidelines on using antigen tests” to leave isolation, like in Biden’s case, said Amy Barczak, an infectious-disease expert at Massachusetts General Hospital. Her research on her suggests that one-quarter of people infected with an omicron variant could still be infectious after eight days.

The CDC guidance dates to the wave of illness caused by the omicron variant that began in December and sickened tens of millions of people in a matter of weeks, causing daily cancellation of thousands of commercial airline flights and leading to staff shortages in all sectors of the economy. Under immense pressure to keep essential services from being hobbled, and amid signs that omicron was less likely to cause severe disease in a largely vaccinated population, the CDC shortened its recommended isolation period from 10 days to five.

Rapid tests were in short supply at that point, but then the federal government expanded its acquisition of tests, with millions now available. Since this spring, Americans have been able to go to a government website, covid.gov, order free rapid antigen tests and have them shipped to their homes. At drugstores and at online retailers, a package of two tests generally costs about $25, depending on the location. Private insurance is supposed to cover purchases of at-home tests.

Some elements of the CDC guidance may prove confusing.

The CDC says that people who choose to take a coronavirus test after Day 5 and get a positive result should extend their isolation to 10 days. But the agency does not directly recommend taking a test after Day 5. The guidance as written says, in effect, you can take a test after five days but be prepared to handle the result. People for whom isolation is a hardship may see no incentive to learn whether they are still shedding viruses.

Experts say the CDC should recommend what’s best for public health.

“That’s kind of the feeling they’re giving off right now: … ‘It’s an okay idea, but we don’t want to actually recommend it,’ ” Mina said. “It should be the other way around.”

The expected release by the CDC of revamped covid guidance in coming weeks is prompted by a desire to provide clarity, according to administration officials and others familiar with the discussions, who spoke on the condition of anonymity because the guidance is not final.

“We just know that people are hungry for guidance at this time,” one CDC adviser said.

The new guidelines are intended to help consumers determine covid risk by evaluating several factors, including whether they will be around people with frail immune systems or other underlying conditions, whether they will be outdoors or indoors, and the quality of the ventilation.

CDC has more than 600 websites related to its covid response, each with different messages on testing, ventilation and masking in different settings, the adviser said. The agency wants to share “important messages that everyone needs to hear in all settings across the country … and then make sure that all of the other guidance underneath it reflects those key messages.”

In the meantime, people testing positive at home past Day 5 are trying to figure out whether it’s safe to go back to work or resume other activities.

How quickly a rapid test turns positive can help guide behavior, Mina said.

“If you have a really dark line that shows up in five seconds before the control line even shows up… you probably really want to stay in isolation,” Mina said. “If you start to see the line in 10 seconds, and it gets really, really dark, you are teeming with viruses.”

If there is a weaker or fainter line, “it’s likely that you have less virus there, but you still do have virus. And there’s no way to define the cutoff at which you’re likely to transmit to other people,” Barczak said.