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Quarantines Won’t Save Us From Coronavirus

Coronavirus is coming. Maybe not for you, but certainly for the U.S. The country’s first case of unexplained origin has been identified in California, and Americans need to prepare, according to the Centers for Disease Control and Prevention.

That it has arrived also means that the virus slipped past China’s efforts to contain it — which included some of the most extreme quarantines in modern history. And that comes as no surprise to public health experts.

“There are reasons to be skeptical of the efficacy of quarantine, for respiratory diseases [like coronavirus] in particular,” said Wendy Parmet, director of the Center for Health Policy and Law at Northeastern University Law School. Quarantine is one of the oldest defenses societies have had against disease, but it’s not a sure-fire way to stop a disease from spreading and shouldn’t be any government’s knee-jerk response. In fact, in some circumstances, a quarantine could actually make things worse.

The first quarantines date at least as far back as the 14th century, when the Croatian city of Dubrovnik began isolating travelers and merchants — even apparently healthy ones — in a special area outside the city and away from all contact with locals. The separation period lasted 30 days. If you hadn’t come down with the plague by the end of that time, you could come into the city.

But tradition isn’t a good enough reason to keep doing a thing. Evidence would be a good reason, but when it comes to quarantines there isn’t much to show that they’re a good idea.

“I think part of the problem is that we don’t really make a distinction between quarantine and isolation,” said Lauren Sauer, a professor of emergency medicine and the director of operations with the Johns Hopkins Office of Critical Event Preparedness and Response. Isolation — separating sick people from healthy ones — is unequivocally a good idea, she and Parmet both said. Research has shown that physical barriers are better at preventing the spread of disease than drugs. When you hear about Americans who have tested positive for coronavirus being “quarantined” in Omaha’s Nebraska Medical Center biocontainment unit, that’s really isolation, not quarantine. A true quarantine is like the original in Dubrovnik, one that sweeps up everybody who might have been exposed to a disease, whether or not there is any evidence they’ve actually contracted it. In other words, what happens when you leave nearly 4,000 people, sick and healthy alike, on a coronavirus-infested cruise ship. (That did not go well.)

Cruise ships aside, true quarantines are fairly uncommon in modern times, Sauer told me. American citizens evacuated from Wuhan, China are the first people to fall under a federally mandated U.S. quarantine in 50 years. Widespread quarantines are so rare, in fact, that we don’t have a whole lot of evidence whether they (or, she added, travel and movement restrictions) even work at all. When the Chinese government decided to restrict travel in and out of more than a dozen cities and confine people who may have been exposed in special centers, they were implementing quarantine on a scale experts called unprecedented. It was, in other words, a really big experiment and we don’t know the outcome yet.

But we can look at history and see that quarantines have not been universally effective, Parmet said. “It’s very hard to make a quarantine that isn’t leaky,” she told me. That becomes truer the larger the area and number of people you’re trying to quarantine. Partially that’s because even the risk of quarantine can set up incentives for people to leave the area before the quarantine happens — which make it harder to know who has been in contact with infected people and where they went. During the 2003 SARS epidemic in Hong Kong, police locked hundreds of people inside an apartment block — but the lockdown came after most of the residents had already fled the building. The Taiwanese government later reported that its own quarantine had contributed to public panic and been counterproductive.

What’s more, once quarantines are in place, they are routinely broken. During the same SARS outbreak, the city of Toronto established a quarantine that, by the city’s own estimates, was followed by only 57 percent of the people affected. After the outbreak subsided, analysis revealed that the city’s quarantine had missed dozens of people who did develop the disease and was simultaneously locking down at least 25 times more healthy people than it should have. That’s not just restricting those people’s freedoms unnecessarily — it’s also trapping them in close contact with actually infected people. SARS turned out to not be super easy to transmit person to person through casual contact, but it’s easy to imagine a more contagious illness where quarantine could result in more people getting sick — not fewer.

Meanwhile, Parmet said, quarantines like the ones implemented in China against coronavirus limit access to supplies, food and (ironically) medical care. We might never know how many people died from coronavirus versus other things,” she said. “The diabetes patients who can’t get insulin. The cancer patients who can’t get medications. The most dangerous thing is a badly run quarantine.”

That’s not to say there’s absolutely no benefit to quarantines and travel restrictions. They do seem to have some ability to slow the spread of disease, Sauer said. Experts have said the Wuhan restrictions probably delayed the spread of coronavirus. And a 2014 study found evidence that a 60 percent reduction in international air traffic could delay the spread of Ebola by up to a few weeks. And delay can be a valuable commodity — if you use it well. It’s time that other countries can use to stockpile medications, prepare hospitals, and help citizens get ready for situations like school closures. It could even, in some cases, buy the time to come up with a vaccine.

But that time is created by people who have to struggle through the medical, social, and economic consequences of a quarantine without benefiting from it themselves. People who are surviving Wuhan’s restrictions are buying benefits for us in the United States — and neither Parmet nor Sauer were certain we were using that time well. While other countries have tested thousands or even tens of thousands of people for coronavirus, the U.S. has only tested a few hundred. We might not even know the extent of the virus already here. “Good things are happening in a lot of places,” Sauer said. “But we’ve misused the time in terms of getting diagnostics and clinical trials up and running. I’m not sure why. Why don’t we have it? And why aren’t we doing more to make sure if we don’t, we’re developing the capability? It’s embarrassing frankly and it’s dangerous.”


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Maggie Koerth is a senior science writer for FiveThirtyEight.

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