With more than a half-million Americans being officially diagnosed with Covid-19 every day, the need for clear guidance on isolation and quarantine is critically important. Sadly, the guidance from the US Centers for Disease Control and Prevention is continuously changing, confusing and at times contradictory.
Dr. Gerald Harmon, president of the American Medical Association, said in a statement Wednesday that the agency’s latest guidance threatens to allow the virus to spread further, putting patients and the health care system at risk.
The most recent CDC recommendations also highlight a persistent problem throughout the pandemic: a lack of available testing and a fundamental misunderstanding of how these tests are designed to work.
As things stand now, people with Covid-19 are asked to:
- Stay home for at least five days
- End isolation if symptoms are resolving
- Wear a mask around others for five more days
Testing at the end of five days of isolation with a rapid antigen test is optional.
So what should you do? I suggest a simple and effective strategy that relies on both testing and clinical symptoms, distinguishes between those who are vaccinated or not, and still allows for a rapid return to normal life if you’re well.
Let’s address the CDC guidance one by one.
Stay home for at least five days
The chance that you’re still infectious drops as time goes on. The longer you stay isolated, the less likely you’ll expose someone else to the virus. Ten days after testing positive, the percentage of people still contagious is estimated to be about 5%, according to researchers at the UK Health Security Agency.
However, at day five, the end of the CDC isolation period, a significant percentage of people (31%) are still contagious. By day seven, the percentage of people still contagious drops by half – to about 16%.
End isolation if symptoms are resolving
Unless you’ve been asymptomatic, this means your symptoms are noticeably better, and importantly, you have been without a fever for 24 hours without taking any fever-reducing medicines, such as acetaminophen or ibuprofen. It is clear that some symptoms, like fatigue and loss of smell, may last a longer time.
Wear a mask around others for five more days
While the CDC surprisingly still recommends three ply-cloth masks, many experts say they aren’t adequate, especially given how easily Omicron spreads: up to three times faster than Delta, according to recent research from Denmark. Erin Bromage, an associate professor of biology at the University of Massachusetts Dartmouth, reminds us that this is primarily an airborne virus and not spread so much by droplets, as happens with flu. Citing data from the American Conference of Governmental Industrial Hygienists, Bromage says a cloth face covering has 75% inward and outward leakage. Compare that with an N95 or KN95, which are excellent at filtering not only large droplets but up to 95% of particles in the air.
Dr. Abraar Karan, an infectious disease fellow at Stanford, once told me that if the American public wore N95 or KN95 masks in public for just four weeks, we could essentially end the pandemic.
These masks are now in plentiful supply, and organizations like the nonprofit Project N95 can help you find the right one, while also making sure they are legitimate.
Optional rapid antigen test around day five
The CDC’s latest guidance says a person in isolation can take an antigen test toward the end of the five-day isolation period, if they have access to a test and want to take one.
Making these tests optional has been the largest source of confusion in the new guidelines. It undermines their value for identifying when you’re contagious and doesn’t seem to consider all the evidence.
“With hundreds of thousands of new cases daily and more than a million positive reported cases on January 3, tens of thousands – potentially hundreds of thousands of people – could return to work and school infectious if they follow the CDC’s new guidance on ending isolation after five days without a negative test,” warned Harmon, the AMA president.
“A negative test should be required for ending isolation after one tests positive for COVID-19. Reemerging without knowing one’s status unnecessarily risks further transmission of the virus.”
So what should the clearest and most evidence-based isolation guidance look like? Given the paucity of tests, it would be both a test-based and symptoms-based policy that reflects the real-world data on someone’s level of contagiousness at any given time. It would also consider the person’s vaccination status.
Consider this approach we have decided to take at my home institution, Emory Healthcare, where I am a practicing neurosurgeon.
Employees who are vaccinated can end isolation:
- At day 5, if an antigen test is negative and symptoms are resolving, (including no fever for 24 hours – off of fever reducing medicines like acetaminophen)
- Or at day 7, if symptoms are resolving; no test is required
Employees who are unvaccinated can end isolation:
- At day 7, if an antigen test is negative and symptoms are resolving, (including no fever for 24 hours – off of fever reducing medicines like acetaminophen)
- Or at day 10, if symptoms are resolving; no test is required
While it is true that vaccinated people may at times be as contagious as unvaccinated, there are two important points to remember:
- The vaccinated are five times less likely to become infected in the first place.
- If a vaccinated person does become infected, the length of time they are contagious is shorter.
It should go without saying that if you are sick, you should stay home, no matter what day you’re on. These rapid antigen tests are most useful in people who have Covid-19 or have been recently exposed but feel fine, which describes many of the people currently isolating or under quarantine.
But the CDC has unfortunately minimized the value of these rapid antigen tests by making them optional. Dr. Thomas Tsai of the Harvard T.H. Chan School of Public Health says the ideal strategy would be to use these rapid tests every day, which can eliminate a lot of the guesswork.
“We’re relying on the symptoms to point to how infectious you are, versus data from antigen tests to say if you’re infectious or not, regardless of your symptoms,” Tsai said.
A single antigen test might not be ironclad, but using them serially over a few days boosts their value even more. It is a strategy that is already working to keep some kids in school instead of quarantining them after they’ve had contact with someone who has tested positive for Covid-19.
The reason rapid antigen tests are often discounted is because they might return a negative result at the same time a PCR test is positive. Most PCR tests take longer and require a lab; they’re highly sensitive and able to detect the presence of the virus’ genetic material long after someone is no longer contagious. Rapid antigen tests can be performed at home and detect certain proteins from the virus, when the viral load is high enough.
The tests are fundamentally answering two different questions. PCR: Do I have any presence of virus or viral remnants? Rapid antigen: Am I contagious? Dr. Rochelle Walensky acknowledged this back in the summer of 2020, before she was director of the CDC.
The differences in the tests seem like a subtle point, but it’s an important distinction.
If antigen tests were ubiquitous, everyone could test themselves regularly in the morning, and know whether they were presently contagious and whether they should continue to isolate.
The real problem with this strategy, however, is an incredibly frustrating one: Two years into this pandemic, these tests are still difficult to find.
I, along with other experts like Tsai and epidemiologist Dr. Michael Mina, have been calling for more tests from the start of the pandemic. In fact, when looking back at our reporting from the past two years, I’ve talked about the need for increased testing more than 650 times.
Yet here we are.
I think Tsai describes America’s relationship with testing the best: “It’s always documented the course of the pandemic as opposed to altering the course.”
The Biden administration is attempting to course-correct, pledging to make 500 million home tests available for the public for free. However, we still have only assurances that they are on their way.
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“Deliveries of tests from manufacturers to the US government will begin over the next week or so. Americans will start receiving free tests in the coming weeks,” said White House Covid-19 response coordinator Jeff Zients during a briefing Wednesday.
But for those who needed them before the holidays and need them right now, we are only hearing story after story of waiting hours to get tested or going on a treasure hunt to hopefully find them in stores. And the cost adds up as well: now about $20 for a two-pack.
If you have Covid-19, it’s worth decreasing the risk of spreading it by really thinking about how you’re going to come out of isolation. I support a strategy that considers your symptoms, your vaccination status, testing and the best data on your contagiousness at any given time.
I am confident that 2022 will be a year of promise and renewal and that we will get through this together. While Covid-19 is likely here to stay, these simple strategies can help accelerate the end of the pandemic.
