So, last week, I made some comments about projections of Ebola numbers for the next few months. Today, maybe worth mentioning two more things that have come up.
NPR interviewed Jim Yong Kim, Head of the World Bank, and broadcast the interview this morning. Some members of congress called for travel restrictions yesterday, and Kim responded essentially that travel restrictions were pointless, using the analogy that they were like stuffing wet towels under a door when you're in a house that's on fire. I've heard many other commentators make similar arguements -- "Don't stop travel because it won't work and it will do lots of harm."
I believe these kinds of comments care a large degree of group-think in them, analogous to "to-big-to-fail" dilemma that emerged in the 2008 financial crisis. Ebola is a terrible infectious disease. We'd like to stop it's spread. But it is spreading and doing harm, and right now, we have very few options on the table for our response. We have no vaccine, and no well-established treatments. The only thing we can really do right now is collect people into hospital wards where they receive basic treatment, and do not put others at risk. That and adopting other hygene and distancing practices that will slow the disease spread, and maybe even stop it.
But we WILL get a vaccine! It's going to take some time, but people can survive ebola infection and they appear to become atleast temporarily immune after they recover, so we should be able to elicit that immunity with a standard vaccine. We can have a high degree of confidence in the scientists and lab workers around the world doing this for us, if we give then the time, money, and resources they need.
So, back to Mr. Kim's analogy of being stuck in a house on fire and stuffing wet towels under the door. It's a good analogy. The house represents the whole world, and wet towels are like travel restrictions. Stuffing wet towels under a door won't put out the fire, but we don't need to put it out -- we only need to keep it at bay until the fire department arrives. If we can use travel restrictions to slow or even stop the spread of ebola into new nations, that buys the scientists more time to make that vaccine we so badly need.
I agree with Mr. Kim's comments in the sense that travel-restrictions should only be a small part of the conversation about Ebola control. And it might be quite hard to prevent international dispersal of the virus, and there may be some adverse consequences to our efforts. But we have to ask ourselves the question, "Is $10 million dollars to high a cost to prevent a nation from having it's own Ebola epidemic? What dollar figure would be too big a cost to protect a nation?" There are some deep questions about our civiliations here that we should not dismiss so easily.
Chuck Haas came out with a comment on estimation of the quarantine window of 21 days for ebola. This is an important issue. The classically used exponential distributions are not good models, and we don't have good mechanistic alternatives. The 21-days seems to be working well, but it may not work perfectly, and we should expect some exceptions to appear. It would be great if we ever could put together better estimates.