Science

The CDC’s Defense of Its New COVID Guidelines Is Complete Nonsense

Close-up of Walensky speaking
CDC Director Rochelle Walensky in Washington on Nov. 4. Chip Somodevilla/Getty Images

The Biden administration has spent much of the past two days trying to defend its widely pilloried new guidelines for how long Americans should isolate if they contract COVID-19. So far, the effort hasn’t been very convincing.

With case counts surging amid the omicron wave, the Centers for Disease Control and Prevention on Monday cut its recommended isolation and quarantine time from 10 days down to five for people who are asymptomatic or for those whose “symptoms are resolving.” After that, people can return to normal life, but should wear a mask for an additional five days, according to the agency.

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The reduction makes some sense: In recent weeks, a number of public health leaders have suggested that 10 days of isolation was excessive, especially for the vaccinated, and that the wait time could perhaps be cut by half given a negative test. Other countries have taken a similar approach; in England, for instance, individuals only have to isolate for seven days if they come up negative on consecutive rapid antigen tests.

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The key in those arguments and policies, though, is the negative test. The CDC’s new guidance, in contrast, does not recommend a test before exiting isolation. This is a huge difference—one that could mean many, many people exit a period of careful isolation only to walk around and spread the highly contagious virus. The most generous feedback could be described as “partially supportive.” Experts have mostly described the CDC’s decision as “reckless,” not based in science, and “bullshit.”

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In response, administration officials have since embarked on a media tour to try and justify the new guidelines. CDC Director Rochelle Walensky told CNN that the agency chose five days because that’s typically the period when individuals are most infectious. “Those five days account for somewhere between 85 to 90 percent of all transmission that occurs,” she said. “So we really wanted to make sure that most of those five days were spent in isolation.” What about the transmission that can happen on later days? Five days, Walensky said, was the amount of time “we thought people would be able to tolerate.” Anthony Fauci, currently the chief medical adviser to President Joe Biden, was even more frank: “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,” he explained on CNN. That is, we need people to get out of isolation so that they can get back to work.

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These are fine rationales for significantly cutting the amount of time people isolate—if they test negative before they leave isolation. After all, there’s no point in making workers call in sick (and potentially forcing their employers to shut down) if they’re unlikely to be contagious. And given that spending 10 days in isolation is incredibly disruptive, it’s possible that the old, longer quarantine recommendation might have discouraged some people from even getting tested for COVID in the first place.

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What’s baffling is that the CDC isn’t asking people to test out of isolation, particularly with home tests. As Eric Topol of the Scripps Research Translational Institute has written, there’s enormous variation in how long individuals remain contagious with COVID, meaning that even after a five-day wait, some people will still spread the disease. And while masks might help reduce that risk some, it’s unclear how much good they’ll do with preventing the spread of omicron, given its high level of infectiousness.

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Antigen tests, however, are very good at detecting people who are still infectious to others. Ashish Jha, the dean of Brown’s school of public health, calls them “contagiousness tests”: They won’t detect every speck of virus that their PCR counterparts are attuned to do, but they can detect the important part—if someone is producing enough of the virus that they’re likely to spread it. Plus, they do not require a drive to a testing site and a wait of hours or days for results. “It makes no sense,” Topol told me of the CDC’s omission. “Rapid antigen tests are perfect for this.”

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Here’s how Walensky defended the decision to not recommend rapid tests, to CNN:

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We opted not to have the rapid test for isolation because we actually don’t know how our rapid tests perform and how well they predict whether you’re transmissible during the end of disease. The FDA has not authorized them for that use. We don’t know how they perform. So what we said was, well, if you got a rapid test at five days and it was negative, we weren’t convinced that you weren’t still transmissible. We didn’t want to leave a false sense of security. We still wanted you to wear the mask. And if it was positive, we still know the maximum amount of transmission was behind you. We still wanted you to wear a mask. And given that we were not going to change our recommendations based on the result of that rapid test, we opted not to include it.

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This is nonsensical on a few levels. The Food and Drug Administration doesn’t have to greenlight every single specific use of a medicine or a test for doctors to use it. We allow Botox for migraines and aspirin for strokes, for example. And while it’s true that we don’t know with absolute mathematical certainty how well rapid antigen tests detect contagiousness at each stage of COVID, that’s hardly a justification for tossing them aside. If a patient tests positive, it means they are still producing lots of the virus, which is a very good reason to worry that they could still be infectious to others. Sure, perhaps someone could test positive without being contagious—but it seems worth erring on the side of having people stay isolated, versus sending them out into the world with a mask. “They’re used in the U.K. and all the other countries that have relied on rapid tests for well over a year, just for this reason,” says Topol. “They have a protocol for self-isolation until your rapid tests convert into negative. So to question that is preposterous, because that’s been well established and validated.”

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“It’s much better than no information,” he added. “It’s exceedingly better than no information. It’s blind to do it without a test.”

The worry that some Americans might use a false negative as an excuse not to wear a mask when they leave isolation is both paternalistic and out of touch. It’s possible, sure, that some folks would test negative and then choose to ignore a recommendation to mask up. But the CDC could also just try giving clear, honest instructions about why people should still mask up for five days, even if they think they’re negative. Plus, does the CDC really think the guidance they have issued will help Americans happily and reliably wear masks? It seems more likely that people who have been following the letter of the law when it comes to coronavirus guidance will continue to do so, and those that are against masking will continue to be against masking.

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Given how weak the CDC’s arguments are, it’s hard not to suspect that the real reason it opted not to recommend taking a rapid antigen test is that the kits are simply too hard to find in the U.S. right now. Walensky has denied this: “This really had nothing to do with supply. It had everything to do with knowing what to do with the information when we got it,” she told CBS. But it makes vastly more sense than the official explanation, which is that U.S. health authorities have decided every other country is wrong and rapid testing just isn’t that useful for figuring out whether someone might still be capable of spreading the plague after five days at home.

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Even if the CDC had recommended testing after five days, some Americans obviously wouldn’t have bothered with it because of the hassle (plenty aren’t bothering to isolate at all). The tests are expensive to have lying around just in case you need to isolate, and can require effort to even find in stock. “The sad reality is that we’re two years into the pandemic and we still have a scarcity of tests in the U.S,” the director of the World Health Organization’s Collaborating Center on National and Global Health Law told NBC. The Biden administration’s failure to make rapid testing widely available would be haunting our response no matter what.

But given that many employers rely on the CDC’s guidelines for when workers can return to their jobs after catching COVID, there’s a good chance these new, looser rules are going to result in more infections, which could end up disrupting people’s lives and businesses just as much as requiring infected individuals to test negative or stay home a couple extra days. The CDC’s nonsense justifications don’t make that any less of a frustrating reality.

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