On March 11, 2020, President Trump banned travel from Europe to the United States for 30 days to slow the spread of COVID-19. Travelers who are legally allowed to enter the U.S., such as U.S. citizens and their families, are now undergoing screening procedures to test for COVID-19 when they reenter the U.S. at one of 13 airports. Various news media report that thousands of these travelers are waiting together for several hours in close quarters for their checked bags and several additional hours to clear customs.
Air travel is an issue that often captures our attention when we feel vulnerable to national security threats. Terrorist incidents that involve aviation security, such as the events of Sept. 11, 2001, the shoe-bomb attack in 2001 and the airport attack in Brussels in 2016 naturally cause us to more closely scrutinize aviation security.
Infectious disease is no different than a terrorist threat when it comes to perceived solutions. Air travel restrictions were imposed after the 2014 and 2016 Ebola outbreaks. After the 2014 Ebola epidemic, the World Health Organization (WHO) ultimately found travel restrictions to be ineffective since Ebola has a long incubation time and early symptoms are not specific. However, even when we put aside the particulars of the Ebola virus, researchers have found that restricting air travel is not the best approach for controlling the transmission of infectious disease. Self-imposed travel restrictions by would-be travelers, such as canceling and reducing non-essential travel, has substantially reduced the transmission rate between countries prior to travel bans being put in place.
As of March 15, 2020, there are more than 162,000 confirmed COVID-19 cases worldwide and over 6,000 deaths. As of now the U.S. officially has over 2,815 confirmed cases and 59 confirmed deaths with the pandemic continuing to spread. COVID-19 is a global pandemic, and health experts indicate that air travel restrictions are unlikely to prevent new cases from entering a country. In fact, countries with strict air travel bans have instead acquired COVID-19. Air travel restrictions impose high economic and social costs while impeding the delivery of relief aid. The WHO recommends against blanket international air travel restrictions, and the Centers for Disease Control and Prevention (CDC) recommends canceling or rescheduling non-essential travel to high-risk areas.
Allowing international air travel while screening for COVID-19 is not a simple or straightforward policy. Due to the long incubation period, most passengers with COVID-19 may not yet show symptoms or test positive for the virus. As a result, widespread testing for COVID-19 ultimately will not catch all sick individuals from entering a country and spreading the disease. The CDC reported finding one infection among 46,016 travelers from China after three weeks of testing. Testing every passenger for COVID-19 will be a massive effort to identify very few passengers who test positive for the virus. Massive testing of air travelers comes at an additional cost, since the tests themselves are a limited resource. Using tests on low-risk, asymptomatic air passengers means fewer tests are available for individuals at high risk.
Screening everyone very thoroughly only works if there are adequate resources to do the screening. At airport screening stations, when there are inadequate resources, queues form. Queues are dangerous in a pandemic, because many people waiting in close proximity provide numerous opportunities for COVID-19 transmission among those waiting in line for screening. A single infected traveler entering the U.S. can become 10. Without enough screening resources, more infected travelers will enter the U.S. by imposing the new screening methods aimed at keeping the infected travelers out, reversing the intended effect of the screening policies.
So what is a sensible approach to air travel in response to COVID-19?
We can learn from previous missteps as well as from policies from the CDC and the WHO. Instead of banning overseas air travel, a more sensible approach would be to adopt simple, risk-based data collection and monitoring procedures in response to COVID-19. This approach uses data to reduce COVID-19 transmission and targets scarce resources to individuals and communities most severely impacted by the virus.
Officials can adopt a policy that involves gathering information about passengers and disseminating information to travelers. Passengers should be asked a few specific questions about their symptoms, where they have traveled in the last 14 days and whether they have had contact with any individuals who have tested positive for coronavirus. This data should be collected and stored to later contact travelers about their symptoms, trace the transmission pathways, identify others who might be exposed to the virus and more quickly contain new infections.
Importantly, screening for COVID-19 should be minimal to keep the line moving so that the travelers can start self-quarantining by staying home for 14 days as per the CDC’s guidelines. This approach would also give officials the opportunity to disseminate information about how to contain the virus through social distancing, emphasizing the importance of self-monitoring your symptoms and making sure the public is aware of who to contact if they have a reason to believe they have had contact with the virus.
These efforts can help infected travelers who are asymptomatic more effectively self-quarantine and reduce exposure to non-infected individuals to control the spread of new infections. Now is the time to apply known procedures for controlling contagious disease rather than adopting knee-jerk policies such as a travel ban. Policies that put data to work will ultimately be more effective than policies based on fear.
Laura A. Albert, Ph.D., is a professor of Industrial and Systems Engineering at the University of Wisconsin-Madison in the College of Engineering. Albert has experience solving real-world problems with application to homeland security and emergency response using mathematical modeling, optimization and advanced analytics.