Quarantine hotels have been around a lot longer than Covid. Credit: JAIME REINA/AFP via Getty Images

July 28, 2021   6 mins

During the pandemic, the words “isolation” and “quarantine” have been somewhat elided. But it’s useful to distinguish between them: if you definitely have a disease and you’re kept apart from everyone else, you’re in isolation; if it’s uncertain whether you have a disease but you’re separated for a while just to be safe, you’re in quarantine. The crucial difference is the element of uncertainty in the latter — and it’s this uncertainty that obsesses the authors of a new book about quarantine.

Husband and wife Geoff Manaugh and Nicola Twilley did most of the research for Until Proven Safe before the Covid-19 pandemic struck. Perhaps they felt strangely lucky, then, as the world descended into the current age of lockdowns and self-isolation, their study of “the history and future of quarantine” taking on a sharp new relevance.

Reading the book, there’s a case to be made that the just-to-be-sure quarantining began in fourteenth-century Dubrovnik, where travellers from areas known to be infested with the Black Death weren’t allowed to enter the walled city until they’d spent a month on a nearby small island. Similar schemes were adopted for maritime visitors to Venice, where you can still visit the lazarettos — quarantine hospitals — that were built especially for this purpose. Even lacking the germ theory of disease, the powers-that-be in these ancient cities intuited that separating was a way of protecting.

In the modern era, with a much better understanding of germs, we sometimes quarantine humans when we don’t really believe it’s necessary: recall the famous photo of the Apollo 11 astronauts, having just returned from their successful moon landing, meeting Richard Nixon from behind a window in a sealed metal box. They were quarantined for three weeks just in case they’d brought back some unknown alien pathogen from the moon — even though it was strongly suspected that (as we now know) the surface of the moon was sterile, and no such pathogens existed.

We’ve been less strict when it comes to the animal kingdom, where we can see some of the most drastic consequences of not quarantining playing out. Think of the episode of The Simpsons where Bart sneaks his pet bullfrog into Australia, whereupon it promptly escapes, reproduces, and devastates all the crops in the country. Manaugh and Twilley remind the reader of the UK’s terrible foot-and-mouth disease crisis in 2001, which originated in pigs who had been fed illegally imported pork from Asia. They also describe how Florida’s citrus industry has been in decline for years due in large part to the insect pest known as the psyllid. Only extremely strict quarantine of incoming plants by the state of California has stopped something similar happening to its famous oranges.

And remember the “friendship tree” that Donald Trump and Emmanuel Macron planted on the White House lawn in 2018? Being from France, its roots were specially wrapped in plastic so as not to spread anything nasty to the US — and it was immediately dug up and sent for a two-year quarantine as soon as the cameras were switched off. (In a definitely-not-metaphorical development, it died before it was returned).

It might seem to be stretching the term, but we quarantine some non-living objects, too: containers of radioactive waste are “quarantined” deep underground until they’re no longer dangerous. That, as Manaugh and Twilley explain, might be a very long time — long enough that scientists have tried to develop universal signs and symbols to communicate with civilisations thousands of years in the future who might have languages very different from our own: “there is bad stuff here – it is dangerous”.

So, animal, vegetable, and mineral: we routinely quarantine them all. Until Proven Safe argues that quarantine is a fundamental part of how societies deal with uncertainty. The lazaretto, the quarantine greenhouse and the concreted-over mine facility full of radioactive waste are, as the authors put it, “what results when abstract arguments over risk are given architectural form” — our best attempts at seeking the certainty we so badly need in the face of terrifying, and sometimes existential, dangers.

But the book left me with one massive unanswered question. If quarantine is such a well-understood process, with such a long history, how come we fumbled it so badly during Covid-19?

The will-they-won’t-they history of the UK Government’s decisions about border quarantine is recounted in a long document by the Home Affairs Select Committee from August 2020. As the disease began to spread outside of China in February last year, our government put in place some relatively light measures: those who had been in Wuhan, Iran or some parts of South Korea were asked nicely to stay at home after arrival at a UK airport, even if asymptomatic; those who had been in Northern Italy or a few other locations where cases had been found did “not need to undertake any special measures” unless they had symptoms. Even though there was to be no UK lazaretto, at least there was a gesture towards keeping incoming high-risk guests apart from the population at large.

Then, on 13 March, this advice was completely dropped. As the outbreak began to spread into Europe, our government decided to remove some of its advice for border quarantines. As a Select Committee report five months later put it: “The decision to lift all Covid-19-related guidance for international arrivals on 13 March, just as other countries were expanding their border measures, is inexplicable.”

It would be 10 days until the first lockdown began in the UK — ten days in which thousands of people with Covid-19 entered the country and wouldn’t have had to isolate at home (as everyone would, when lockdown later came in), and certainly wouldn’t have to be tested as they arrived at the border. Even after lockdown began, there wasn’t the slightest question of us instituting a mandatory quarantine, despite other countries at the same time requiring incoming travellers, few though there were by this time, to stay locked in a hotel or other special facility for periods of as many as 21 days (that being, at one point, the length of the mandatory quarantine in Hong Kong). Incredibly, the UK only began a mandatory hotel-based quarantine on 15 February 2021 — and only for some countries — more than a full year since the first Covid case arrived on our shores.

Calling the decision inexplicable is understandable. But let’s try to explain it. Perhaps some thought that, since border measures like quarantine wouldn’t stop all cases, they weren’t worth instituting. This all-or-nothing argument has certainly been made in other contexts — for masks or even vaccines — and it betrays a magic-bullet mentality: defeating a contagious disease takes a lot of different measures, none of which will ever be 100% effective. Manaugh and Twilley note the irony that if a quarantine works — if it stops disease transmission — then it will in retrospect be seen as an overreaction.

Was quarantine thought to be a bit too disruptive, a bit too difficult, to institute? Perhaps, though of course we did eventually end up instituting it, and if the story of vaccines has shown us anything, it’s that we can move mountains to get something done if we feel we really have to.

Were some scientific advisers, and perhaps politicians, unable to decouple the idea of border quarantine (or indeed travel bans) from politically-unpalatable views in their minds? The authors of Until Proven Safe do note the political angle: treating foreigners, immigrants, or refugees as if they were carriers of disease (or were a disease themselves) has been the preserve of authoritarian, racist, populist leaders. Could an innate aversion to being like those bad people have skewed the experts’ judgement?

There is some evidence for this, with Sage fretting early in the pandemic that border measures would need to be “draconian” to hold back the spread — a choice of words that clearly indicated disapproval. In fact, those measures may have been the proverbial stitch in time that would’ve saved, well, a lot of lives — and to draw comparison between actions taken during a pandemic emergency and those in “normal” times is irrational in any case.

Or maybe there’s an even more disturbing explanation: that quarantines weren’t instituted because, at the start of the crisis, the UK’s scientific advisers thought it would be a good thing if as many people as possible caught the disease. The idea that a strong quarantine system could render the “herd immunity” plan unnecessary doesn’t seem to have occurred, even though it did to policymakers in Hong Kong, New Zealand and elsewhere.

In any case, few of the lessons from history described in Until Proven Safe were applied during the history we’ve just lived through. The simple idea that “keeping people in quarantine, even if you’re not sure they’re infected, helps to hold back a contagious disease” seems to have been lost in the morass of counter-intuitive thinking that swirled around the start of the pandemic.

Maybe we can learn the lessons for next time: what of the future of quarantine? Manaugh and Twilley say that it might not look like quarantine at all. They discuss DARPA’s Prometheus project, where the idea is to develop a way of predicting whether someone, once infected with a disease, will be contagious. One of the nastiest things about Covid is, of course, that people can still spread the disease before seeing any symptoms — if they get symptoms at all. Such a system could help us pinpoint the people who need to be isolated — and would, to return to the theme, help reduce a big source of uncertainty.

But anyone who’s had a visit to the pub cancelled because of the UK’s “pingdemic” should know that technological solutions are wont to go awry; we can predict endless angry debate over the rate of false-positives and false-negatives from a Prometheus-like system should it ever come to be used. Far from putting all our eggs in technology’s basket, we should be open to the central point of Until Proven Safe: although the low-tech idea of setting possibly-contagious people apart could be made more effective, more equitable, and more humane — we wouldn’t have a history so full of quarantine if it didn’t really work.

Stuart Ritchie is a psychologist and a Lecturer in the Social, Genetic and Developmental Psychiatry Centre at King’s College London