A dispute has flared between those who support travel restrictions and those who do not. While some proponents can be faulted for excessive confidence in their effectiveness, opponents can be faulted for demanding that they be perfectly effective to justify adoption.
For Americans, Ebola infection is a low probability event with extraordinarily high consequences. This has become evident when two health care workers who cared for Liberian Thomas Eric Duncan contracted the virus despite substantial protective gear and sanitation practices. A less publicized but similarly worrisome case is the NBC freelance cameraman who contracted Ebola in Liberia and has now been declared free of the virus after aggressive treatment. The cameraman thought he had avoided contact.
All three cases indicate that experts have underestimated or underreported the risk of infection. This appears to be true for health care workers, who are highly exposed absent extraordinary measures, and others who may only be near persons who are contagious.
Numerous elected officials, both Republicans and Democrats, have proposed travel restrictions. The Obama administration and the Centers for Disease Control oppose such restrictions, saying that they would not be effective and preferring to take temperatures of arriving travelers.
The administration’s position on travel restrictions is not a firm one, however. On October 21, Department of Homeland Security Secretary Jeh Johnson announced additional travel restrictions beyond those put in place last week:
Last week, with the Centers for Disease Control and Prevention, DHS implemented enhanced screening measures at five airports around the country – New York’s JFK, Newark, Dulles, Atlanta and Chicago. Passengers flying into one of these airports from flights originating in Liberia, Sierra Leone and Guinea are subject to secondary screening and added protocols, including having their temperature taken, before they can be admitted into the United States. These airports account for about 94 percent of travelers flying to the United States from these countries. At present there are no direct, non-stop commercial flights from Liberia, Sierra Leone or Guinea to any airport in the United States.
Today, I am announcing that all passengers arriving in the United States whose travel originates in Liberia, Sierra Leone or Guinea will be required to fly into one of the five airports that have the enhanced screening and additional resources in place. We are working closely with the airlines to implement these restrictions with minimal travel disruption. If not already handled by the airlines, the few impacted travelers should contact the airlines for rebooking, as needed.
Denials notwithstanding, this constitutes a travel restriction. It differs insofar as it screens actual passengers here rather prospective passengers there, and thus it tolerates s different mix of errors. Curtailing flights or denying visas to prospective travelers from Liberia, Sierra Leone and Guinea achieves a very low rate of false negatives (i.e., allowing infected persons from these countries to travel to the US) and a very low risk of transmission to third parties in flight at the cost of a very high rate of false positives (i.e, disallowing travel to the US by persons who are not infected). In contrast, DHS’s old travel restrictions achieved a very low rate of false positives at the cost of a high rate of false negatives and concomitant transmission to third parties in flight.
In any case, the choice of how to achieve any public health objective while balancing false positives and false negatives is not a scientific or economic question. It’s a policy decision, one that both science and economics can inform but not determine. Unfortunately, so far public discussion has been almost bereft of both science and economics.
DO TRAVEL RESTRICTIONS REDUCE RISK?
Yes. That’s why the CDC is trying to quarantine those who may have been exposed. How much international travel restrictions would reduce risk is an empirical question that depends largely on how they are designed and implemented. But it is simply wrong to assert that they would be ineffective unless it is presumed that such restrictions would be designed or implemented badly. Interestingly, travel restrictions were an integral part of what Nigeria and Senegal did to successfully eradicate Ebola within their borders.
WOULD TRAVEL RESTRICTIONS ELIMINATE THE RISK FROM EBOLA?
No, but there aren’t any public health measures that can achieve this goal. That includes the DHS/CDC strategy of conducting temperature screening at selected US airports. Asymptomatic travelers will not be detected. Nor will persons infected who do not display symptoms until after the assumed 21-day incubation period is over. (A recent paper by Drexel University environmental engineer Charles Haas shows that risk of transmission may be substantially greater than zero after 21 days.)
Assertions that [insert regulatory intervention] “won’t work” appear to be premised on the presumption that 100% effectiveness is the appropriate standard by which to judge competing regulatory options.
IS FEDERAL POLICY BASED ON SCIENCE?
It does not appear to be. To date, experts at the CDC have displayed too much confidence in what they think they know and too little respect for what they don’t. Their efforts to calm public fears have violated best practices in risk communication. As a result, the experts are now widely regarded as incompetent, politically motivated, or both.
IS FEDERAL POLICY BASED ON ECONOMICS?
Probably not, but the nature of Ebola risk may limit the useful application of economic tools. To the extent that policy makers must deal with public fear and outrage at officials who seem arrogant or supercilious, economics may best be used by providing a framework for understanding the unintended consequences of whatever actions might be contemplated.
ARE PROPONENTS AND OPPONENTS CONSISTENT?
Consistency is often an early casualty of crisis. Nonetheless, it is intriguing to note that many of the most vocal proponents of travel restrictions tend to be skeptical of regulation in other situations. Conversely, many who oppose travel restrictions tend to be credulous of the effectiveness of regulation generally. Examples are not hard to find.
Among supporters and opponents of travel restrictions, many of the former are well known to be skeptical of regulation generally while many of the latter are similarly well known for supporting regulation with few limits. As for President Obama, his opposition is significantly at odds with positions he has taken on other risks. For example, in his 2013 attempt to impose secure new legislative restrictions on firearms after Sandy Hook, the White House asserted on his behalf, “If even one child’s life can be saved, then we need to act.”
Elected officials views of the merits of travel restrictions, like their views of regulatory matters generally, often display partisanship. Of the 87 legislators who were reported yesterday by Howard Koplowitz of the International Business Times as supporting travel restrictions are reported, 76 are Republicans. The Hill’s Mike Lillis says House Democrats are leading the opposition, and it appears the ranks of opponents include no Republicans. While it is easy to blame elected officials for partisanship, a great deal of Ebola reporting and commentary has been overtly partisan. So it cannot be easily discerned whether elected officials are behaving in a partisan manner (and reporters are accurately covering it) or they are responding to partisan reporting and punditry in predictable ways.