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So You Tested Positive for COVID. How Long Should You Quarantine?

The CDC has dropped the recommended isolation period from 10 to 5 days for asymptomatic people with COVID. But many public health officials disagree.
A man receives a nasal swab during a test for Covid-19 at a street-side testing booth in New York on December 17, 2021.
A man receives a nasal swab during a test for Covid-19 at a street-side testing booth in New York on December 17, 2021. (Photo by Ed JONES / AFP) (Photo by ED JONES/AFP via Getty Images)

The Omicron variant of COVID-19 is sweeping through the United States with unprecedented speed, now making up the majority of cases across the country.

Hundreds of thousands of Americans are testing positive for COVID every day at a rate that has already surpassed last winter’s deadly peak, before vaccines were readily available. 

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But on Monday, the Centers for Disease Control and Prevention issued new guidance shortening the recommended quarantine period for people who test positive but aren’t showing symptoms from 10 days to just five, with a recommendation to wear a mask for an additional five days. “These updates ensure people can safely continue their daily lives,” CDC director Dr. Rochelle Walensky said in a statement accompanying the guidance. 

But the science is far from settled on the question, and some public health experts and epidemiologists have come out against the CDC’s new guidance.

“I never dreamed the day would come when I would advise people NOT to follow their guidance. Breaks my [heart],” Dr. Jerome Adams, who was the U.S. Surgeon General from 2017 to 2021 under former President Donald Trump, said in a Tuesday tweet. “But ask any of them. They wouldn’t even follow it for their own family.”

Harvard epidemiologist Michael Mina called the decision “reckless.”

“CDC’s new guidance to drop isolation of positives to 5 days without a negative test is reckless. Some (people) stay infectious 3 days, some 12,” he wrote on Twitter.

There’s a plethora of unclear information and seemingly contradictory guidance surrounding the new variant. So what are the millions who are going to test positive for  COVID-19 in the coming weeks supposed to do?

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How long should I quarantine?

It’s important to reiterate off the bat that the new guidance shortening isolation periods for people who’ve tested positive is meant only for people who are not showing symptoms. After five days, if the person is “asymptomatic at that time,” they can then leave isolation, the CDC says. 

If you have a fever, you should stay home until your fever resolves, according to the CDC. 

If you’ve been exposed to COVID-19 via a close contact and you’re unvaccinated or unboosted and more than six months out from your second shot, you should quarantine for five days and then isolate for another five, the CDC says. If you have gotten a booster shot, the CDC says, you should mask for 10 days but you shouldn’t need to quarantine. 

It’s worth pointing out that the new guidelines issued by the CDC call for a shorter isolation period than almost any other G8 nation, as well as no requirement to test out of that isolation. Canadians in most provinces, for example, can expect to quarantine for 10 days if they test positive. And while the United Kingdom recently rolled out new guidelines also reducing isolation periods, it was reduced to seven days, not five.

Additionally, in order to end their isolation period, UK citizens have to produce two negative results with the first coming no earlier than six days into isolation.

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The big problem with doing that here, of course, is that testing in the U.S. is currently abysmal. There are long lines for the PCR tests which are more accurate, even if the person is asymptomatic. And in recent weeks there has been a mad rush for antigen rapid tests—which do a good job of detecting positive results from people at or near the peak of their symptoms—driving a shortage of those tests. (The FDA also said Tuesday that preliminary research shows that some of these tests may be less sensitive at detecting the new variant, meaning they may produce more false negatives.) 

President Joe Biden said earlier this month that the federal government would make 500 million at-home testing kits available for free beginning next month, but we’re still several weeks away from that. 

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"It's clearly not enough. If I had—we had—known, we would have gone harder, quicker, if we could have," Biden told a group from the National Governors Association this week. "We have to do more. We have to do better, and we will."

What counts as symptoms in the world of Omicron?

Most people who return positive will never truly know which COVID variant they contracted, as your test result won’t show which variant you tested positive for. And besides, the U.S. has a low rate of genome surveillance compared with countries like the U.K. and Denmark. 

Some of the Omicron symptoms are similar to the classic COVID symptoms we’ve seen in previous variants: congestion, fatigue, coughing, and a fever. 

With that said, there are reports and early research indicating that the symptoms may slightly differ. For example, a loss of taste and smell—one of the early key indicators of COVID-19 cases—appears to be rarer in people who’ve contracted the Omicron variant

And the ZOE Covid symptom tracker app in use in the U.K. has found, via self-reported symptoms from hundreds of thousands of people, that the top five symptoms among people who’ve contracted either the Omicron or Delta variant, are more similar to traditional cold symptoms: headache, fatigue, runny nose, a sore or scratchy throat, and sneezing.

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The bottom line is the same as it’s been since the even if you suspect your sluggish feeling or headache is just a cold—or a hangover— you should get tested. 

Why is the CDC’s guidance changing?

The CDC says the new guidance is “motivated by science demonstrating that the majority of SARS-CoV-2 transmission occurs early in the course of illness,” i.e. as many as two days before the onset of symptoms and up to three days following the beginning of symptoms. 

There’s also a growing body of evidence suggesting that the incubation period for Omicron has gotten shorter, perhaps due to the sheer transmissibility of the illness—compared with Delta, Omicron replicates inside of human respiratory tract tissue as much as 70 times faster, according to a recent study published by the University of Hong Kong.  

But public statements from top Biden administration officials have indicated the change in guidance is rooted as much in politics and economics as public health. "The reason is that with the sheer volume of new cases that we are having and that we expect to continue with Omicron, one of the things we want to be careful of is that we don't have so many people out," Dr. Anthony Fauci, the White House chief medical officer, said in a CNN interview Monday.

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"Obviously, if you have symptoms, you should not be out [of your house],” Fauci said. “But if you are asymptomatic and are infected, we want to get people back to the jobs, particularly those with essential jobs, to keep our society running smoothly.” 

Biden has continued to maintain that the federal government will not urge lockdowns such as those we saw early on in the pandemic, and on the Monday call with governors said that there was “no federal solution” to the pandemic and that it would be solved with “state level solutions.” 

When asked by MSNBC’s Chris Hayes Tuesday about the science backing up the CDC’s assertion that asymptomatic people can leave quarantine after five days, Fauci responded: “"Nothing is going to be 100 percent, and this is one of those situations, when you're dealing with a very difficult situation, that we often say you don't want to be the perfect to be the enemy of the good.” 

Fauci added that you have a “higher likelihood” for “most people” of shedding the virus within those first five days than any other time, and that another lockdown was “not palatable to the American people.”

The new changes quickly followed an update issued last week, when the CDC said that healthcare workers can return to work after seven days in quarantine if they’re asymptomatic and test negative, or in the case of a staffing crisis, five days.

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“There are no data or evidence to back [the new guidance] up,” Dr. Eric Topol, an executive vice president at Scripps Research, said in a Tuesday Substack post. “Yes, we’re facing an Omicron onslaught of cases and it would be useful to come up with a strategy to avoid a mass loss of functionality among our workforce and the on-the-go public, no less in the midst of the holiday season. But that doesn’t justify issuing a vacuous guideline.”

Even before the CDC issued its newest round of guidance, the National Football League altered its guidelines to no longer require vaccinated players to test weekly, after more than 100 COVID cases across the league left teams shorthanded and forced the rescheduling of three games. And less than a week before the guidance was issued, Delta Airlines CEO Ed Bastian sent a letter to the CDC asking the agency to shorten the quarantine period for breakthrough COVID cases to five days, Reuters reported

"With the rapid spread of the Omicron variant, the 10-day isolation for those who are fully vaccinated may significantly impact our workforce and operations," Bastian wrote, noting that more than 90 percent of Delta employees are fully vaccinated. "Similar to healthcare, police, fire, and public transportation workforces, the Omicron surge may exacerbate shortages and create significant disruptions."

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Thousands of flights, both domestic and overseas, were canceled around the holiday weekend. In addition to inclement weather, some airlines—including Delta—have said that the rapid spread of Omicron impacted the cancellations. 

Sara Nelson, the head of the Association of Flight Attendants (AFA) union, slammed the CDC’s decision in a Monday statement. "We said we wanted to hear from medical professionals on the best guidance for quarantine, not from corporate America advocating for a shortened period due to staffing shortages,” Nelson said. ‘The CDC gave a medical explanation about why the agency has decided to reduce the quarantine requirements from 10 to five days, but the fact that it aligns with the number of days pushed by corporate America is less than reassuring.” 

Is Omicron worse or better than Delta?

The jury is still out.

First, it’s important to note that the CDC’s initial estimate of how prevalent Omicron is in the United States has been significantly adjusted downward, as Politico reporter David Lim noted Tuesday. The CDC estimated last week that for the week ending December 18, Omicron was responsible for more than 70 percent of all sequenced COVID-19 cases. 

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But since then, the CDC has updated its data to show that, at that point, Omicron made up fewer than a quarter of all cases nationally. This means Delta—which was responsible for the surges this summer and fall—would have been responsible for the majority of U.S. cases, although the proportion of Omicron to Delta varied greatly by region; in the region covering New York, for example, the CDC estimates that more than half of COVID cases at that point were Omicron.For the week ending December 25, however, Omicron was responsible for nearly three-fifths of all new cases, according to the CDC’s current data. 

Much of what we know so far about Omicron is based on research in other countries whose waves began sooner, such as Denmark, the U.K., and South Africa, where the variant was first discovered by researchers. In those places, doctors and researchers have noted that while hospitalizations have increased, they aren’t increasing at the same rate they did with other previous waves. 

Some studies have suggested that Omicron does not attack the lungs in the same way Delta or other variants did. But it’s so far unclear whether the lower hospitalization rate in these countries is due to built-up immunity from vaccinations and prior infections, decreased virulence in the disease caused by Omicron, or some combination of the two. 

What is clear, however, is research showing that those who’ve been vaccinated, and especially those who’ve had booster shots, are much less likely to require hospitalization due to COVID-19. The CDC cited U.K. data indicating boosters provide up to 75 percent efficacy against Omicron infections, though data from the same country indicated that efficacy can wane by as much as 25 percent after 10 weeks. Israel is currently conducting research on the effectiveness of a second booster

And if you are one of the unlucky people who’ve gotten vaccinated and then tested positive regardless, there are encouraging signs that the immunity generated could help protect from other variants. One study by researchers at Oregon Health and Science University earlier this month found that the antibodies generated from a breakthrough case were more than 1,000 percent effective than the antibodies generated from a second shot of the Pfizer vaccine. 

“You can’t get a better immune response than this,” Dr. Fikadu Tafesse, the senior author on the study and an assistant professor of molecular microbiology and immunology in the OHSU School of Medicine, said in a press release. “These vaccines are very effective against severe disease. Our study suggests that individuals who are vaccinated and then exposed to a breakthrough infection have super immunity.”