Air travel bans to control epidemics

On rare occasions, diseases that are both deadly and easily transmitted are a concern to regional, national, and international health authorities, and of governments at all levels. This is because someone who is infected with that disease is a plane ticket away from any other part of the world, making deadly epidemics a concern not only for the medical community, but also the airline industry.

There are many established methods for systematically halting the spread of a disease within a population that is in a defined geographical area, including restricting travel to or from an area affected by an epidemic. While a travel ban has been shown to be a very effective disease control method where the local or regional authorities can limit the movements of the population that is at risk from the epidemic , it is much less effective, and possibly counterproductive, when applied to airline travel because it is much harder to limit the movement of airline passengers.

Goals of a travel ban
The goal of an air travel ban would be to prevent someone who is infected from spreading a disease to a distant population where that particular disease is often either very rare or not present at all.

The travel ban can be considered a risk management effort where the risk to be avoided isn't the disease itself, but the use of air travel as a means to spread the disease. Like most risk management efforts, there would be three basic goals:

  1. Prevent the risk from occurring: This is the ideal goal, which would be reached if the travel ban prevented all infected passengers from contacting the unaffected population.
  2. Make the risk less likely to occur: This would happen if at least some infected travelers were prevented from flying.
  3. Lessen the effects of the risk should it occur: This might be the case if an infected person were to their destination in spit of the ban, but were prevented from having extensive contact with the unaffected population.

Of these three goals, only the first two can be directly achieved by a travel ban. The third would only happen if the travel ban were combined with another process for managing passengers who made it to their destination in spite of the travel ban.

What exactly happens in an air travel ban?
A travel ban to prevent the spread of an epidemic can take many forms, including the following:

  • Banning all airline service to or from an area affected by an epidemic.
  • Banning individuals from traveling to or from an area affected by an epidemic.
  • Barring individuals who had recently lived in or visited an area with an active epidemic, but are flying in from an unaffected area.
  • Barring individuals from flying who are likely to spread the disease, specifically anyone

While not strictly part of the travel ban, in order to meet the third goal of this risk management effort, the travel ban should be combined with a process to deal with someone who arrived in spite of the ban. Typically, that may include the monitoring of someone who may have been exposed to the disease.

If the passenger has been diagnosed as having the disease, shows symptoms of the disease, or has definitely been exposed to the disease causing agents, then the passenger would likely be isolated from the general population, and if necessary given appropriate medical attention.

Why air travel bans are difficult to enforce
The nature of air travel and the air travel industry makes it difficult or impossible to create an effective air travel ban. Just some of the reasons include the following:

  • Identifying an ill, infected, or exposed passenger: Unless a passenger is exhibiting symptoms of a disease or admits to having been infected by or exposed to the disease, it may be very difficult to identify a risky passenger either before or after a flight. For example, a passenger may be unaware if he or she had been exposed to any disease causing agents. Also, in most cases, if a passenger is about to board an outbound flight or has just arrived on an inbound flight, it is very difficult to test a passenger who is not symptomatic for a disease and to have the results come back in a reasonable time.
  • Lack of passenger incentives: Because of the costs and inconveniences a passenger may face if banned from flying, that passenger may take actions from changing travel plans to outright lying in order to keep from being affected by a travel ban.
  • Lack of legal authority: Depending on the situation, a government or civil aviation authority that wants to implement a ban may have very little or no legal or regulatory authority to force an airline, airport, or national government to implement necessary elements for an effective ban, including compelling passengers to provide details of all of their activities.
  • Identifying a passenger's travels: A passenger's ticket or reservation for an individual trip may say very little about where they may have recently lived or visited, and it is very difficult for an airline or government to independently verify all of a passenger's recent travels.
  • Speed of implementation: The legal, logistical, and bureaucratic process of implementing a travel ban to address a particular epidemic may not be able to keep up with the evolving nature of the threat.
  • Unwanted side effects: Because the organizations and individuals who may be instrumental in combating an epidemic may rely on the airlines to travel to or from an area affected by a travel ban, that ban may make it that much harder to control the epidemic.

The following example illustrates some of the challenges and difficulties authorities face when implementing a flight ban.

US response to the Ebola epidemic of 2014
During the summer and fall of 2014, Ebola, a deadly disease caused by a virus and spread primarily through contact with virus-laden bodily fluids, killed thousands of victims, the vast majority of which were the the west African countries of Liberia, Sierra Leone, and Guinea. Only a small number of infections and deaths happened outside of Africa.

By the end of October 2014, there was only one Ebola death in the US, which was from someone who was infected in Liberia and traveled by air to the US. There were also two people who were infected by Ebola in the US, and both had been involved with the treatment of the person who died.

US government passenger screening
In mid-October 2014, the US government implemented a screening process to check travelers flying to the US from Liberia, Sierra Leone, and Guinea for either Ebola-like symptoms, or exposure to the Ebola virus. The screening program was in effect for the five US airports that accounted for about 95% of the travelers to come to the US directly from those countries. This program was consistent with the risk management goal of lessening the effect of a risk, specifically making it less likely that someone exposed to or infected by Ebola would also expose the general population to that disease.

On October 21st, the US Department of Homeland Security updated this screening process by requiring all travelers from Liberia, Sierra Leone, and Guinea who are flying to the US to enter the country through one of these five cities.

Reasons a ban may have been impractical
While there were demands from some quarters, primarily from the political arean and from social media, for a ban on travel to and from the three most affected African countries, no ban has been implemented as of late October 2014. The reasons for this inaction may have been in part due to the following realities faced by the US government:

  • No US airline provides direct service to Liberia, Sierra Leone, and Guinea, and the US government had no legal authority ban flights to the affected countries by non-US airlines.
  • US citizens and permanent residents are allowed to travel to Liberia, Sierra Leone, and Guinea without prior approval from the US government.
  • In order to ensure that no travelers from Liberia, Sierra Leone, and Guinea enter the US, there would have to be some kind of screening program in place for every traveler flying into the US, since travelers from Liberia, Sierra Leone, and Guinea may have either begun their trip to the US from outside those three countries.
  • Banning international travel to or from Liberia, Sierra Leone, and Guinea would have done nothing to address domestic flights by taken by those already in the US who were recently in one of those three countries.
  • Several thousand US residents who regularly travel between those three countries and the US are medical professionals, civil servants, military personnel, and others who are part of ongoing efforts to control the Ebola epidemic.

CDC advice for airlines and airports
Interim guidance for airlines
Infection control for cabin crews
Advice for airline cleaning crews
Exit screening procedures
Protective equipment for airport screeners
Protective equipment for law enforcement
Evaluating returned passengers
Informational resources

Diseases and air travel on air travel bans
Background information on Ebola
Background information on SARS

Travel warnings and advisories
CDC travel health advice
US State Department travel warnings
UK Foreign and Commonwealth Office
Canadian government travel advice
Australian government travel advice

Air travel bans to control epidemics -- Revised 20 October 2014