Are we at a stage yet where we can answer counterfactual questions about what would have happened if all international flights had been shut off in January (Assuming away the political problem)?
Assuming away the political problem of making it stick, it seems clear that without universal border closures by countries, it would have made only a minor difference in spread—most cases that came to Europe, the US, and elsewhere didn’t come from China.
If some set of countries were willing to completely shut down all borders, those countries might have avoided infections—might, but I’m skeptical. Even now, the countries that shut down international travel still have a fair amount of international travel, from diplomatic travel to repatriation of citizens to shipping and trucking. So it could plausibly have delayed spread by a month. In places that mounted a really effective response, a month might have made the difference between slow control and faster control. In most places, I think it would have shifted spread a couple weeks later.
Yes it has always been clear to me that shutting down travel from one specific place where you think the disease is is not going to work.
Here in Europe, I have had to postpone personal vacations because the borders have indeed been shut and are only now reopening. Given that Europe actually did close its borders, both external and internal, do you think that it would have been a good idea to go ahead and do that in January, assuming away the political problem?
Again, it didn’t actually stop spread—it slowed it slightly. Borders haven’t been actually closed. Flights have continued, you just need connections to get a visa. But people have been able to return home—and dual citizens have been able to travel both ways—the entire time.
So do you think that the actual travel restrictions that happened were just a waste of time, and we should have had fully open borders?
Or do you think that the restrictions that we had (late and partial) were the optimal disease-fighting policy (again, neglecting political considerations)?
In general, I think that earlier closures would potentially have delayed spread enough to save lives due to getting vaccines and testing further along than they were.
I’m also claiming that now, with a fully in place and adequate test-and-trace program, including screening for passengers and isolation for positives, border closures have low marginal benefit. Without such a test and trace program, travel modifies the spread dynamics by little enough that it won’t matter for places that don’t have spread essentially controlled. The key case where it would matter is if the border closures delayed spread by long enough to put in place such systems, in which case they would have been very valuable. And yes, border closures in place have allowed this in some places, but certainly not the US or UK.
So, conditional on the policy failures, I think border closures were effectively only a way to signal, and if they distracted from putting in place testing and other systems by even a small amount, they were net negative.
But what about the ~3 months of lockdown and massive Economic disruption that we had to go through? Don’t you that that could have been avoided by closing our borders tightly in January? Do we have evidence to either confirm or exclude that now?
If every country in the world had closed their borders well enough to stop all movement before it left China, yes, spread would have been prevented. But that’s unfeasible even if there was political will, since border closures are never complete, and there was already spread outside of China by mid-January.
Once there is spread somewhere, you can’t reopen borders. And even if you keep them closed, no border closure is 100% effective—unless you have magical borders, spread will inevitably end up in your country. And at that point, countries are either ready to suppress domestic spread without closures, or they aren’t, and end up closing later instead of earlier.
Good post David!
I applaud posts like this. It’s a great tradition that we do them.
I believe the conversation about border closures was with me on Twitter?
Are we at a stage yet where we can answer counterfactual questions about what would have happened if all international flights had been shut off in January (Assuming away the political problem)?
Assuming away the political problem of making it stick, it seems clear that without universal border closures by countries, it would have made only a minor difference in spread—most cases that came to Europe, the US, and elsewhere didn’t come from China.
If some set of countries were willing to completely shut down all borders, those countries might have avoided infections—might, but I’m skeptical. Even now, the countries that shut down international travel still have a fair amount of international travel, from diplomatic travel to repatriation of citizens to shipping and trucking. So it could plausibly have delayed spread by a month. In places that mounted a really effective response, a month might have made the difference between slow control and faster control. In most places, I think it would have shifted spread a couple weeks later.
Yes it has always been clear to me that shutting down travel from one specific place where you think the disease is is not going to work.
Here in Europe, I have had to postpone personal vacations because the borders have indeed been shut and are only now reopening. Given that Europe actually did close its borders, both external and internal, do you think that it would have been a good idea to go ahead and do that in January, assuming away the political problem?
Again, it didn’t actually stop spread—it slowed it slightly. Borders haven’t been actually closed. Flights have continued, you just need connections to get a visa. But people have been able to return home—and dual citizens have been able to travel both ways—the entire time.
So do you think that the actual travel restrictions that happened were just a waste of time, and we should have had fully open borders?
Or do you think that the restrictions that we had (late and partial) were the optimal disease-fighting policy (again, neglecting political considerations)?
In general, I think that earlier closures would potentially have delayed spread enough to save lives due to getting vaccines and testing further along than they were.
I’m also claiming that now, with a fully in place and adequate test-and-trace program, including screening for passengers and isolation for positives, border closures have low marginal benefit. Without such a test and trace program, travel modifies the spread dynamics by little enough that it won’t matter for places that don’t have spread essentially controlled. The key case where it would matter is if the border closures delayed spread by long enough to put in place such systems, in which case they would have been very valuable. And yes, border closures in place have allowed this in some places, but certainly not the US or UK.
So, conditional on the policy failures, I think border closures were effectively only a way to signal, and if they distracted from putting in place testing and other systems by even a small amount, they were net negative.
But what about the ~3 months of lockdown and massive Economic disruption that we had to go through? Don’t you that that could have been avoided by closing our borders tightly in January? Do we have evidence to either confirm or exclude that now?
I don’t understand the hypothetical.
If every country in the world had closed their borders well enough to stop all movement before it left China, yes, spread would have been prevented. But that’s unfeasible even if there was political will, since border closures are never complete, and there was already spread outside of China by mid-January.
Once there is spread somewhere, you can’t reopen borders. And even if you keep them closed, no border closure is 100% effective—unless you have magical borders, spread will inevitably end up in your country. And at that point, countries are either ready to suppress domestic spread without closures, or they aren’t, and end up closing later instead of earlier.