Why are countries still introducing COVID-19 quarantines for travelers from affected regions, even though it's been proven they don't work?

Question

Various governments seem to be playing whack-a-mole with travel restrictions and mandatory quarantines in the recent COVID-19 epidemic. First Chinese residents were banned from numerous countries. Afterwards travel bans expanded to South Korea, Japan, Iran and most recently Italy. Yet despite all the travel restrictions, the virus managed to successfully spread out all across the globe.

So why continue with the practice of restricting foreign travel, especially when the virus has already been identified to be spreading at the local level? E.g. why doesn't the US remove travel restrictions on Chinese visitors, given that the virus has already been detected in numerous states?

Update from Mar 21: There are now 10 thousand official cases in the US, but travel restrictions are still in place for some reason.

Update from Sep 1: There are now 6 million+ cases, but people from China, Brazil and the Schengen are are still banned from the US

Update from December 2021: here we go again! Numerous travel bans on South Africa despite Omicron already being everywhere.

Update from January 2023: now Chinese travelers are being asked to get tested for no good reason

Answer 1

While it has clearly been shown by the virility of the virus so far that travel restrictions will not stop the inevitable community spread of the illness, and that their effectiveness as impeding the spread of the virus is small, the aim of the policy is no longer to stop the virus, but to delay it. This was confirmed as current policy in the UK's response to the virus by the Chief Medical Officer, Professor Chris Whitty, on March 5th.

There are a few reasons why this is the goal of many governments. Firstly, if the peak of the pandemic can be delayed, this allows plans to be put in place for management of the crisis. For example, in the UK, plans have been floated that would allow final year medical students and trainee doctors to take on hospital duties during the nine week period that the virus is currently predicted to have the highest effect on the NHS, in order to mitigate the strain on the service.

Secondly, delaying the spread of the virus allows time for a vaccine to be developed. While research on this is progressing quickly, it will still take time for the vaccine to pass clinical trials and be approved for human usage. In addition, as @Patricia Shanahan points out in the comments, the effectiveness of existing drugs already approved for treating similar respiratory diseases can be evaluated, which could be ready sooner than developing brand new drugs or a vaccine.

Finally, as health services are acknowledged as being under the most strain during the winter months, the best time for the pandemic to peak would be in the middle of summer.

To this end, the policy of travel bans, while having been shown to be relatively ineffective at preventing the spread of the disease outright, is being used to delay the spread of the virus as much as possible, to allow national governments to prepare for the full impact of the peak of the predicted pandemic.

Answer 2

In addition to CDJB's answer, there's an extra reason to delay, delay, delay.

During the SARS outbreak I read, I believe it was John Barry's 1918 Influenza book. A good read, on a number of levels, including the laborious birth of non-quack Western medicine.

He made the point that the influenza became progressively less lethal. I.e. you had better chance of survival a year or so into the epidemic than at the start. Viruses face evolutionary pressure not to kill, or at least not quickly, since they entirely rely on live hosts to be pumping out duplicates.

Something like AIDS doesn't mind so much, since it kills over a number of years so there's a lot of potential to pass on infections. Early syphilis was also more lethal, IIRC. In a way, Ebola is a stupidly lethal and quick virus.

So this virus may very well follow the same path of progressively lesser lethality.

Barry, if it was Barry I read, also repeatedly made the point that quarantines and avoidance of group gatherings did help, and quite a lot.

Update Sept 14: they don't work seems like a rather discredited claim right now. Canada for one would be in a much worse position if it was allowing free entry from the US since that country has not managed to push down its infection rates.

Update May 28: the game has again changed with the appearance of regional variants, often with extra transmissibility and unknown virulence/resistance to vaccines. It seems like restricting in some fashion travel from some highly affected countries is going to be with us for a while yet, even as vaccines make it otherwise less risky to accept travelers from less-impacted countries.

Answer 3

A lot of it surely has to do with reciprocity and not losing face at this point. It is indeed the case that the US (as of August 18, when the CDC page was last updated before this post) was still banning travel from China, pursuant to the January 31 presidential order. But the Trump administration has repeatedly called it "the China virus" or thereabout (including at the RNC), so clearly they'd be losing face to some extent should they lift the restrictions on China (which in the meantime has imposed its own restrictions on the US.)

The EU's position vis-a-vis of China (mostly driven by France's insistence according to the BBC), but also reflected e.g. in the government of Netherlands statement has more explicitly to do with reciprocity at this point:

the ban on travellers from China will be lifted once China allows entry to EU citizens.

So clearly some of the restrictions have stopped being purely medical and have turned political. That's not to say they are entirely political. When the EU imposed/revised its new standards this summer, the number of infections in a region was a clear criterion:

The number of new infections must remain at or below approximately 19 per 100,000 inhabitants. Consideration will also be given to contact tracing efforts and the number of coronavirus tests carried out.

In the meantime the number of cases in the EU has increased substantially again, no doubt in large part due to the relaxation of internal infection-control measures... A number of the new restrictions imposed by some EU countries (on each other) were motivated by these developments, e.g.

On Sunday the Czech Republic recorded a daily record rise for the third day in a row, with 1,541 new infections. Neighbouring countries have begun to restrict entry for Czechs, with Germany announcing it would require a negative test for arrivals from Prague on Wednesday.

This is hardly the only example though of such recent changes. Over the summer the UK imposed quarantine on its own citizens returning from Spain, then from France and the Netherlands; at least the Netherlands was explicit in why they answered with similar measures:

A spokesman for the Dutch Ministry of Foreign Affairs said, "This means that Great Britain will receive a code orange as travel advice, because the Dutch have to be quarantined there."

Greece, Denmark, Belgium and Luxembourg (and probably more) imposed a test-taking measure on travelers from Bulgaria and Romania; Italy imposed a outright quarantine on them etc.

If you want to hear recent & explicit argumentation from a country that has almost totally closed its borders (back in April 3 billion people lived in such countries), Hungary has closed its borders to practically everyone, for the month of September, the reason given being that most infections are of "foreign origin":

"From September 1, foreign citizens will no longer be allowed to enter the territory of Hungary," Gergely Gulyás, the prime minister Viktor Orbán’s cabinet chief said during a press briefing.

"There is a risk of introducing the virus and most of the new infections are of foreign origin," he said, adding "Hungary is green, all other countries are now turning red," in reference to the traffic light system.

[...] Hungary's government indicated that the border closure will stay in place for a month.

So you could probably divide the reasons for the lingering and new restrictions in 3 categories:

• old restrictions not re-evaluated for various reasons
• new restriction imposed on countries perceived to be "high risk"
• retaliatory (tit for tat) measures