Some countries slammed their doors. It worked — until they let outsiders back in.
Some countries slammed their doors. It worked — until they let outsiders back in.
This Is Why We Couldn’t Control the Pandemic
ByTomás PueyoNathaniel LashandYaryna SerkezSept. 14, 2020
To stop the coronavirus,the most successfulcountries slammed their doorsshut to visitors. It worked.Until they letoutsiders back in.To stop the coronavirus, the most successful countries slammed their doors shut to visitors. It worked.Until they let outsiders back in.
In March, I wrote two widely read articlesabout the emerging coronavirus pandemic,“Why You Must Act Now,” then “The Hammer and the Dance,” which called for a “hammer” (stringent measures to stop the virus) followed by a “dance” (intelligent but less aggressive actions to prevent the pandemic from coming back).
Since then, many countries have used a hammer: schools closed; businesses shuttered; public events were banned; masks were required; citizens were ordered to shelter at home.
All those actions helped slow the spread of the virus. But as the world failed to dance the right way, it has been facingresurgencesof the pandemic. I’ve been examining the failures  — and what needs to happen next time.
Measures like masks, testing, contact tracing, isolations, quarantines are still necessary, but one approach has not been emphasized enough: the fence. Countries that quickly closed their borders or carefully monitored anyone coming in have been most successful in slowing infections.
Some countries use fences to block outsiders from crossing their borders. Some countries limit travel within their borders. As the United States considersrelaxing some border controlsandEuropeancountriesreimposetravel restrictions, they need to realize that these fences are necessary to control the virus — and if they are enforced, they’ll be effective.
Back in May, the coronavirus was out of control.Brazil,Russiaand theUnited Stateshad noticeably more cases thanJapan,Taiwan and South Korea. You might think this would be because the first three have been more lax in their approach. Certainly, the leaders of these nations were half-hearted — and worse — in handling the virus.
But many regional governments within each country actually imposed quite severe restrictions on activity. This shows Oxford University’s Stringency Index, which zeroes in on the strictest measures in a country, whether part of a national, state or local government response to slow the virus, like closing businesses and limiting gatherings. As you can see,Brazil, Russia and the United Statesrank higher in thestringency of their measures — much stricter, overall, thanJapan, Taiwan and South Korea. Yet those countries still had some of the worst outbreaks in the world.
That’s because their national governments didn’t coordinate a central response, leaving state governments to battle the virus largely on their own.
Some states pursued aggressive actions to slow the pandemic while others took a hands-off approach. Those differing responses hamstrung states that adopted stricter measures, since travel between states continued, undermining the efforts of hard-working governments to suppress the virus, and spreading it throughout the countries.
This is what the active cases per region looked like as they spread through China early this year. The virus expanded  from the epicenter in Wuhan, the capital of Hubei Province, to surrounding regions.
Two weeks after the Jan. 23 lockdown of Hubei Province, 60 percent of all Chinese cases were in Wuhan, 20 percent were in the rest of Hubei and the remaining 20 percent in neighboring provinces.
It’s as if there were concentric circles around the epicenter. The closer you were to it, the more cases you had.
The same thing happened in Italy.
The main outbreak was initially concentrated around Lodi. It exploded, infecting surrounding areas, including Milan.
The government applied a hammer: Shelter-at-home orders were issued, nonessential businesses were closed. The restrictions included a fence: Citizenswere explicitly barredfrom traveling to other parts of the country.
Without travel, the spread froze. The provinces that hadn’t been affected, like those in southern Italy, would be spared. The shape of the map barely changed. Cases just kept going down in every province.
We saw the same pattern unfolding in Spain and France.
Spain
Daily active cases (log scale)
1
10
100
1,000
20,000
Madrid
Spain’s cases start
in Madrid
Travel ban
begins in March
February 15
March 15
Infections seem
frozen
Infections
fade by May
April 15
May 15
And continue
to fall
June 15
France
Daily active cases (log scale)
1
40
1,000
7,000
Paris
The virus
surges
France’s outbreak
takes hold
April 15
March 20
By June,
infections recede
Countermeasures
take effect
June 15
May 15
And continue
to fall
July 15
Daily
active
cases
(log scale)
Madrid
1
10
100
1,000
20,000
Travel ban
begins in March
Infections seem
frozen
Infections
fade by May
And continue
to fall
Spain’s cases start
in Madrid
June 15
February 15
March 15
April 15
May 15
Paris
1
40
1,000
4,000
7,000
France’s outbreak
takes hold
The virus
surges
Countermeasures
take effect
By June,
infections recede
And continue
to fall
March 20
April 15
May 15
June 15
July 15
Daily
active
cases
(log scale)
1
10
Madrid
100
1,000
20,000
Travel ban begins
in March
Infections seem frozen
Infections fade
by May
And continue to fall
Spain’s cases start
in Madrid
April 15
June 15
February 15
March 15
May 15
1
1
1
Paris
40
1,000
1,000
1,000
4,000
7,000
7,000
7,000
The virus surges
France’s outbreak
takes hold
Countermeasures
take effect
By June, infections
recede
And continue to fall
April 15
July 15
March 20
May 15
June 15
Spain
Daily cases by population (log scale)
1
10
100
525
Madrid
Spain’s cases start
in Madrid
Travel ban
begins in March
February 15
March 15
Infections seem
frozen
Infections
fade by May
April 15
May 15
And continue
to fall
June 15
France
Daily cases by population (log scale)
1
10
100
380
Paris
The virus
surges
France’s outbreak
takes hold
April 15
March 20
By June,
infections recede
Countermeasures
take effect
June 15
May 15
And continue
to fall
July 15
Daily
cases by
population
(log scale)
Madrid
1
10
100
525
Travel ban
begins in March
Infections seem
frozen
Infections
fade by May
And continue
to fall
Spain’s cases start
in Madrid
June 15
February 15
March 15
April 15
May 15
Paris
1
10
100
380
France’s outbreak
takes hold
The virus
surges
Countermeasures
take effect
By June,
infections recede
And continue
to fall
March 20
April 15
May 15
June 15
July 15
Daily
cases by
population
(log scale)
1
Madrid
10
100
525
Travel ban begins
in March
Infections seem frozen
Infections fade
by May
And continue to fall
Spain’s cases start
in Madrid
April 15
June 15
February 15
March 15
May 15
1
Paris
10
100
380
The virus surges
France’s outbreak
takes hold
Countermeasures
take effect
By June, infections
recede
And continue to fall
April 15
July 15
March 20
May 15
June 15
Now let’s look at what happened in Portugal, Brazil and Russia.
At first, Portugal did not suffer as big an outbreak as other E.U. countries. Maybe that’s why it was relatively lenient. Portugal did close its land border with Spain, its only neighbor, and imposed stay-at-home orders, but did not explicitly forbid internal movement. Nor did it close its airports to visitors from other E.U. states, the United States, Britain or Brazil.
The result? Hot spots kept igniting throughout the country during the lockdown. The capital, Lisbon, had such a bad outbreak that it had toreimpose stay-at-home orders in the middle of June, when the rest of the European Union was reopening.
By the end of June, when all E.U. members opened their borders to one another, only Sweden — which never applied a hammer — had more cases per inhabitant than Portugal.
Russia
Daily active cases (log scale)
1
10
100
78,000
1,000
Moscow
Russia’s cases start
in Moscow
Infections
don’t stay there
April 1
April 15
They spread east
And get worse
May1
May 15
By June
it’s everywhere
June 1
Portugal
Daily active cases (log scale)
1
10
100
700
Porto
Lisbon
Portugal saw
cases everywhere
April 15
April 1
People kept
traveling
May 15
May1
Cases remained
steady
June 1
Daily
active
cases
(log scale)
1
10
100
Moscow
1,000
78,000
And get worse
They spread east
Russia’s cases start
in Moscow
Infections
don’t stay there
By June
it’s everywhere
May 15
May1
April 1
June 1
April 15
1
Porto
10
100
700
Lisbon
May1
People kept
traveling
July 1
Portugal saw
cases everywhere
Cases remained
steady
April 1
August 1
June 1
Daily
active
cases
(log scale)
1
10
100
Moscow
1,000
78,000
Infections don’t
stay there
They spread east
And get worse
By June
it’s everywhere
Russia’s cases start
in Moscow
May1
May 15
April 1
April 15
June 1
Porto
1
10
100
700
Lisbon
Portugal saw cases
everywhere
May 1
People kept traveling
July 1
Cases remained
steady
June 1
August 1
April 1
Russia
Daily cases by population (log scale)
1
10
600
100
Moscow
Russia’s cases start
in Moscow
Infections
don’t stay there
April 1
April 15
They spread east
And get worse
May1
May 15
By June
it’s everywhere
June 1
Portugal
Daily cases by population (log scale)
1
10
100
1,000
Porto
Lisbon
Portugal saw
cases everywhere
April 15
April 1
People kept
traveling
May 15
May1
1
10
100
1,000
Cases remained
steady
June 1
Daily
cases by
population
(log scale)
1
10
Moscow
100
600
And get worse
They spread east
Russia’s cases start
in Moscow
Infections
don’t stay there
By June
it’s everywhere
May 15
May1
April 1
June 1
April 15
1
1
Porto
10
100
10
1,000
100
1,000
Lisbon
May1
People kept
traveling
July 1
Portugal saw
cases everywhere
Cases remained
steady
April 1
August 1
June 1
Daily
cases by
population
(log scale)
1
10
Moscow
100
600
Infections don’t
stay there
They spread east
And get worse
By June
it’s everywhere
Russia’s cases start
in Moscow
May1
May 15
April 1
April 15
June 1
Porto
1
10
100
1,000
Lisbon
Portugal saw cases
everywhere
May 1
People kept traveling
July 1
Cases remained
steady
June 1
August 1
April 1
In Russia, Vladimir Putin’s government claimed that the situation was “under control,”didn’t manage it centrally, andleft it to thestatesto impose restrictions. Many of themapplied lockdowns;only a fewclosed borders. As a result, the coronavirus traveled for thousands of miles, from the west to the east, in a matter of weeks, and the outbreak persists.
Something similar happened in Brazil. Its president, Jair Bolsonaro,ridiculedsocial distancing measures, suggested the coronavirus waslike a measly cold, and called for the economy toreopen. The states were left todo all the work. They adopted strict measures, including ordering businesses to close, sheltering in place, and limiting public transportation between cities and states. But, crucially,few states closed borders with other states. As a result, the epidemic spread everywhere, starting in the well-connected coast and eventually reaching the remote areas of the Amazon forest.
Now let’s look at what happened in the United States.
The United Statesclosed its bordersto many countries, beginning with China on Feb. 2, followed by Iran a month later, much of Europe in mid-March and Brazil in May. It also eliminated “nonessential travel” from Mexico and Canada in March.
But many of these bans were too late or too lenient. For instance,some 40,000 peopletraveled from China to the United States in the two months after President Trump imposed restrictions. And the Centers for Disease Control and Prevention acknowledged that the ban on travelers from the European Unioncame too lateto prevent widespread community transmission in New York City.
The coronavirus first afflicted mostly cities that are international hubs.
The virus moved swiftly from there. By mid-April, most of the United States was seeing infections, demonstrated here using data on prevalence, the number of active cases by population.
Anonymized cell phone data from this time allows us to see how many travelers passed between metro regions. Using the prevalence of the virus in those places, we can roughly estimate how many of those travelers might have been carrying the virus. Each dot represents100 possibly infected travelers, based on averages of the first two weeks of April.
This is how the virus works: If an area without infections receives visitors from another area that is infected, it will inevitably become infected.
This was one of the earliest lessons from the outbreak that began in New York City and spread outward.Connecticutwas one of the first states to lock down, but that didn’t stop the virus from crossing its southwestern border.
But also considerNew Mexico, which applied one of thelongest-lasting hammers, shutting down schools and businesses and ordering people to wear masks. Even so, cases in Doña Ana County, which borders Texas, began to rise following cases in nearby El Paso.
New Mexico’s lockdown kept a lid on cases in Albuquerque, but didn’t prevent the spread of the virus into theNavajo Nation, which includes portions of New Mexico, Arizona and Utah. The first outbreak of that area was traced toa churchrally in Chilchinbeto, Ariz., inside the Navajo Nation, in March.
The same pattern played out in ruralOregon. In July, cases rose in Malheur County, which sits just west of Idaho’s capital, Boise. Malheur’s health directorsaidthe county’s proximity to populous Canyon, Payette and Washington Counties in Idaho played a pivotal role in the number of local cases.
In Washington, cases initially appeared in the Seattle area. Counties to the southeast were next. Soon, Umatilla County, Ore., suffered its first outbreak. Neighboring counties in Oregon still had low prevalence.Farm workers traveling to Umatilla for the harvestwere the likely seeds.
When the coronavirus appeared in the San Francisco Bay Area,six of its counties ordered a lockdown;  some residentsfled the area to Lake Tahoedespite astatewide shelter-at-home order. Soon after, Washoe County, one of the counties on the Nevada side of the lake, had an outbreak. Of the six original cases that were tracked from outside the county,four were from California, three of them from the Bay Area.
Through July, the virus raged across America’s Southern and Western states.
At the same time, people began traveling more, based on averages from the last two weeks of July. As the number of cases increased across the country, the risk for moreinfected travelersincreased as well.
If people can travel from infected regions to places with few or no infections, infections will spread, no matter how much other work was done to keep the virus at bay. And it only takes a few viral seeds to cause havoc.
Initially, Singapore controlled the virus really well. Unfortunately, it was slow to close its borders with countries other than China. By March, enough seeds were introduced from other countries to cause a huge outbreak, with over 57,000 cases to date, more than Wuhan.
Singapore
Argentina
The same thing happened in Argentina. A few seeds from abroad early on — just about 800 in total — led to over 500,000 cases.
A few infections are enough for a major outbreak. This is why all regions should consider a fence.
Fences are policies that countries or states put in place to keep out infections. There are three types.
Walls, or strict travel bans, are the most aggressive. Most people are barred from coming in, so most infections are prevented. Most East Asian and E.U. countries erected walls by banning citizens from many countries with high infection rates, including the United States.
Quarantinesare less aggressive: Instead of being barred from entering, visitors have to spend several days without social contact until they are cleared. Usually, governments require two weeks of quarantine, but some communities allow people with negative P.C.R. tests (typically done with nasal or throat swabs) to leave quarantine early. Hong Kongis a good example.
The last type of fence is thecheckpoint: Travelers can come in, but they must be assessed individually first.
Quarantines and checkpointsstop many but not all contagious people from spreading the virus. Still, the infections that get through can be more easily controlled.
Taiwan, South Korea, Japan and Iceland all have a wall: They ban people from many countries. For those they let in, they have special types of quarantines.
In Taiwan,for example, on arrival, you must present a negative P.C.R. test taken within three days, provide your phone number to the authorities, go directly into quarantine by private transport orspecial busesthat don’t stop along the way, and stay isolated for two weeks. Twice a day, the government enforces the quarantine by checking on your whereabouts with phone calls. It also tracks your mobile phone. If your phone moves away from the quarantine site or shuts down, the police will show upwithin minutes. If the phone remains in one place for too long,the tracking system might assumethat you left it behind and call you.
South Korea isvery similar, except that it uses an app instead of your phone number to track visitors. It houses foreign travelers in quarantine facilities, which range from run-down government buildings to five-star hotels.
Japanis similar to South Korea and Taiwan, but with less quarantine enforcement — and higher prevalence.Icelandtoo has aweakerprocess and more cases. It allows travelers to avoid the two-week quarantine if they have two negative P.C.R. tests, one on arrival and one five or six days after, with isolation in between.
What about other countries?
For months, most European Union countries banned travel inside their borders and from their E.U. neighbors. Most of these countries got their epidemics under control.
But at the beginning of July, borders between these countries reopened. And now, the E.U. is suffering the beginning of its second wave.
Spain, for example, has awallwith many countries outside of the European Union, but only a weak checkpoint for E.U. countries. Travelers have their temperatures checked and must filla formsharing where they are coming from, their destination address, and whether they have had the coronavirus.
On their own, these steps are close to worthless. People can lie on the form. And temperature checks catch just a small number of cases.
Pre-symptomatics, those who haven’t developed symptoms yet, causeabout halfofall infections. Of those who are symptomatic,20 percent don’t have a fever. And thermometersmight notbe sensitive enoughto catch some of the remainder.
A better checkpoint precaution is a P.C.R. test, which will catcharound 70 percent of cases. Some countries, however, request only that travelers show proof of a negative P.C.R. test performed within the last 72 hours. By itself, this is also almost useless.
A personwill usually test negativejust after being infected. As the illness progresses over the next few days, symptoms may appear and the test is more likely to turn out positive. The peak of contagiousness isaround the fifth day, and the test is most sensitive around the eighth day, catching around 80 percent of cases. This means that people with a negative P.C.R. test 72 hours ago might have caught the virus just before or after the test and are reaching peak contagiousness during travel, or after arriving at their destination.
A test at the checkpoint allows more opportunity to catch infected people. And another P.C.R. test a few days afterward, with a quarantine in between, will also catch those who got infected just before traveling.
What is the United States doing?
Nearly 30 states imposedquarantineson visitors in the last seven months, but there was little or no enforcement. And most states have eased or lifted them. Of the states that turned to quarantines, two of the most interesting are Alaska and Hawaii. The differences are very telling.
Alaskaapplied a hammer when it had around 100 cases. At the end of March, it required all travelers entering the state toself-quarantine, and notablybanned internal travelfor all but essential work or critical personal needs.
Cases plummeted.Alaskastarted reopeningby the end of April.
The state fully reopened in May. But although officials threatened quarantine violators withup to $25,000 in fines and prison time, the rulewas not enforced. Cases started growing, with infections coming in on seafood boats and overtaking food-processing plants and then communities. The prevalence jumped from four active cases per 100,000 people at the end of May to over 200 at the end of July.
Initially,Hawaiifollowed an approach similar to Alaska's. It also issued a shelter-in-place mandate at the end of March, when there were few cases. People flying into the state were required to quarantine. Violators faced fines of up to $5,000 or a prison term of up to one year.
ButHawaiidid what Alaska did not: enforce its quarantine. On arrival, visitors had to identify their hotel, and the authorities called the hotel to make sure guests abided by the lockdown. Sometimes, the government called visitors or checked their social media. Hotel employees and Hawaii residents also alerted the authorities about violators.Nearly 200peoplehave been arrested forbreaking quarantine.
Unfortunately, this system was much weaker than in places like Taiwan or South Korea, and eventually enough cases entered Oahu to spur an outbreak in August.
In the end, it wasn't enough to hold back the tide.
That could be because, in the end, only an estimated 40 percent ofHawaii’svisitors fully respected the state’s measures for their two full weeks of quarantine, based on analysis of anonymized cell phone records of travelers provided by Cuebiq. Hawaii’s quarantine is not airtight.
That's still far more visitors sheltering in place than in Alaska. Initially, they had obeyedAlaska'squarantine, but eventually fewer travelers stayed home.
Other states have asked travelers to self-quarantine voluntarily or have threatened them with fines. In those states, visitors appear to be mostly ignoring the rules.
That would be less of a problem if people were not traveling much anymore. That was the case for a time: Travel dropped precipitously in March and April.
But recently, travel is back to pre-coronavirus levels inAlaska. InHawaii, visitors probably got the memo that theywillhave to quarantine if they visit. Fewer people are coming and going.
Yet the country as a whole has gone the route ofAlaskarather thanHawaii. Travel is above pre-coronavirus levels.
If Hawaii’s system had been as airtightas those of Japan, Taiwan or South Korea, it might have avoided its August outbreak. Hawaii has an obvious advantage over other U.S. states: It’s a collection of islands. Japan, Taiwan and Iceland are also islands; South Korea is nearly one. Nearly all visitors arrive at the airport, making them easier to monitor, which is important becauseair travel has a bigger impact on spreadthan other travel methods.
Yet road trips also propagate the virus, and controllingroad travelis difficult, especially at state borders. How do you enforce restrictions on travel by car?
Nearly all E.U. countries closed their borders and many limited travel within their borders,including very intensely connected areassuch as Belgium, Luxembourg and the Netherlands, and their borders with France and Germany.
E.U. countries simply took it seriously.FranceandSpaineach fined more than one million people for violating the rules. In some cases, the police set up checkpoints, as inFinlandandGermany, and even blocked some roads.
In the United States, such a system could be simple: All people traveling to a state requiring a quarantine would fill out a form before coming in, detailing their travel plans, their quarantine location over the next two weeks, and how to contact them to confirm they are complying. The policy would be enforced through random checks and fines, or through an app visitors would be required to place on their phones to track their whereabouts. (This of course raises privacy concerns.)
They could shorten the quarantine with negative P.C.R. tests, ideally at the time of entry and four days after. Measures could be adapted to the type of visitor and the situation at their place of origin. For example, essential workers like truckers would be exempt, but they would need to minimize contact with others during their stay. Regions that share a low prevalence — “green zones” — could band together to form an area free of fences, but protected by fences on their borders with high-prevalence states.
New York City’s regulations are geared toward this approach. The city has set up checkpoints at major entry points. But theauthorities merely inform visitorsof quarantine requirements. Fines of up to $10,000 are possible but only two people had received summonses for violating quarantine orders as of late last week.Until the city truly enforces its quarantine, visitors will keep visiting, and it’s likely that infections will rise.
Britain also requires quarantines for travelers coming in,but has finedonly around 30 peopleout of millions of travelers.  It took this threatening — but essentiallyworthless— measure against E.U. countries since they reopened their borders to one another in July, with many experiencing more outbreaks. New travel bans andsocial gathering limitshave been imposed. Infections are once again rising in Britain, and new infections seem guaranteed this month, as students go back to school and workers return to their offices.
No country has been able to control the virus without a fence. Fences are not enough to stop the virus on their own, but they’re a necessary part of the solution. European countries and U.S. states had hoped otherwise. They were deluded. They opened their arms to their neighbors too soon and got infected in the hug.
They need to realize that not every country or state is effectively fighting the virus. Why should their citizens sacrifice so much for so long, with lockdowns and business closures, only to waste their efforts when their neighbors visit?
And as long as states fail to control their borders, the coronavirus will come back.
Tomás Pueyo is an executive at Course Hero, an online learning platform based in San Francisco. Nathaniel Lash and Yaryna Serkez are graphics editors in Opinion.
Design byJessia Ma.
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