Schneier on Security

Skeptical • October 25, 2014 4:53 PM

@Adjuvant: You conflate restricting flights to e.g. US from West African countries with the sealing of the borders and ports of West African countries. I’ve got a bridge to sell anybody who thinks it’s effectively feasible to seal, for instance, Liberia’s land borders. As for circumventing bans on certain air travel routes, that’s easy: travel by any means possible to the nearest unbanned international travel hub, then fly to the US. And if you argue that countermeasures can be put in place against that sort of thing based on e.g. passport stamps, I’d ask you to remember that we’re talking about Sub-Saharan Africa here: good luck! Your assessment of this CDC spokesperson’s argument as unconvincing is, itself, unconvincing.

As many people have noted, and as I thought my own criticism of the article explicitly indicated, you don’t need to achieve 100% success for a travel ban to reduce risk. No doubt some people who would have flown will have a passport from an ebola-free country (or at least one that is not the subject of the ban), will elude or defeat border controls, and will board a flight from a non-banned country.

But how many of those 150/day passengers are going to do that successfully? I’d guess not many, and in any event a very reduced number.

Moreover, the substantial additional travel time will mean greater probability that an infected person will progress to a symptomatic, or even incapacitating, stage before being able to get on a flight. This raises the probability that the person will be stopped or detected as a carrier of the virus before exiting border controls in the United States.

.Any increase in friction will reduce the available pool of personnel and supplies to some degree. How much is debatable.

I don’t agree. First, I reject the assumption of increased friction: mandatory coordination with the military and DHS may actually increase the number of personnel and supplies able to travel to West Africa to help by reducing costs for NGOs and by increasing the perceived security of personnel volunteering. Second, I reject that any increase in friction reduces available supply: a doctor intent on volunteering in West Africa is not going to be deterred by some additional paperwork. “Friction” is a metaphor that only goes so far; people and bureaucratic hoops are not actually exactly like objects in a physics problem.

Not at all. The argument is not only that devastating the economies of West Africa is a “bad thing” per se; the corollary is that the comcomitant degradation of what little public health infrastructure exists in those countries would worsen the epidemic, quite overwhelming any benefits that might be gained by the restriction of population movement and contributing to the deepening and broadening of the epidemic.

This is not the argument made in the article however. The argument in the article includes a brief mention of a deleterious effect on public health resources, but focuses entirely on the impact to West Africa. The further argument you make here – that the worsening of the epidemic in West Africa will therefore lead to increased risk of exposure in the US – is not stated in the article. I don’t agree with the further argument here either, incidentally.

Apart from all of the above, try your intuition on a counterfactual. Suppose ebola has mutated and can now be transmitted as readily as influenza. Would you agree that a travel ban would just make things worse for the US, or would the arguments in the article appear somewhat weaker than they do to you currently?

Skeptical • October 26, 2014 8:16 AM

@RonK: Not a trick question. I think the Vox article is a bit breezy in its arguments; they’re easy to accept if you’re not worried and are genuinely concerned about victims of the disease. I happen to fall into that category. But if I were genuinely concerned about ebola becoming epidemic in the US or other countries, I’d take a much harder look at those arguments.

In my scenario, there’d be a full response across the spectrum and in every space. It would include a travel ban.

Thank God, ebola is not so contagious that such a response is necessary.

The real reason not to institute a travel ban is that there’s little threat to the US from ebola and it would make things more difficult in affected countries. Whether this remains politically viable depends on how quickly this can be contained in West Africa, because it will not take many cases of ebola travelling on an international flight for the public to demand a travel ban. Tick tock.