The evidence on travel bans for diseases like Ebola is clear: they don't work

They’re political theater, not good public health policy.

Travel restrictions to control the spread of disease have been tried since 1377, when the Mediterranean city of Dubrovnik — formerly known as Ragusa — imposed a 40-day isolation period on ships entering the city suspected of carrying the Black Death.

With every new pandemic threat come calls to seal up borders. US politicians, including, Chris Christie and Donald Trump, lobbied for a travel ban on West Africa in response to the 2014-2016 Ebola outbreak.

Now, with the World Health Organization’s declaration on Wednesday that an ongoing Ebola outbreak in the Democratic Republic of the Congo constitutes a global health emergency, the WHO’s chief anticipated the specter of travel and trade restrictions would rise again. And he immediately condemned the approach.

They’re “punitive and counterproductive,” said WHO director general Tedros Adhanom Ghebreyesus. They “serve no useful purpose.”

The trouble with using a travel ban to stop Ebola is that it renders useless the two best methods we have for stopping Ebola. Determined people will find ways to cross borders anyway, and if they don’t go through airports or they lie about where they came from, health officials can’t track their movements. And this is an important point because, to fight Ebola, we need to be able to follow up with the contacts of the infected. Getting aid and resources to the region to contain Ebola at the source would also become more challenging with travel restrictions.

To be clear, no one has yet called for travel bans on DRC. But it seems likely some governments or airlines may do so in the coming days or weeks, so it’s worth stating: Health officials unanimously agree they’re a bad idea.

At best, travel restrictions, and even airport screenings, delay the spread of disease but they don’t impact the number of people who eventually get sick. They are expensive, resource-intensive, and potentially harmful to the countries involved. Here’s a guide to the research:

1) Travel bans in the wake of HIV/AIDS didn't stop the spread of the disease

After HIV/AIDS was discovered in 1984, governments around the world imposed entry, stay and residence restrictions on people with the disease. As one 2008 study notes: "Sixty-six of the 186 countries in the world for which data are available currently have some form of restriction in place." In the US, the ban — instituted by President Ronald Regan in 1987 — was only lifted when Obama came into office.

But HIV/AIDS managed to spread anyway, reaching pandemic proportions by the 1990s. This 1989 review of HIV/AIDS travel restrictions found they were "ineffective, impractical, costly, harmful, and may be discriminatory." Prevention of HIV worked better than travel restriction, the authors concluded. "The rapidity and extent of HIV spread in any country is primarily determined not by HIV-infected travelers but by the risk-producing activities of its citizens, regardless of whether HIV is introduced by foreign travelers or returning nationals."
What's more, officials found that screening travelers for disease was an imperfect process that "will erroneously but unavoidably label some HIV-infected travelers as being [HIV-negative]." Barring the invention of a rapid, handheld Ebola test in airports, the same issues and limitations hold today with Ebola.

2) Flight bans post-9/11 did not prevent a deadly and prolonged flu season

Temporary flight bans and decreases in air travel following 9/11 provided a natural experiment in the impact of travel on seasonal influenza. Researchers found the reduced movement of people didn't stop the flu; it delayed it by a couple of weeks and led to a prolonged flu season. So the researchers didn't find that restricting air travel prevented flu spread; only that it delayed it.

The researchers didn't test whether this delay reduced flu cases or saved lives. But a look at the CDC data shows that flu deaths actually massively spiked during the 2001-2002 flu season, rising from about 3,900 the year before to more than 13,000 post-9/11. This isn't to say that 9/11 had anything to do with the increase in flu deaths, but rather that travel bans didn't seem to prevent them.

3) Travel restrictions didn't cut bird flu infections

One 2006 study modeled various approaches for stopping the spread of H5N1 avian flu. It found that restricting travel wasn't effective: "Our simulations demonstrate that, in a highly mobile population, restricting travel after an outbreak is detected is likely to delay slightly the time course of the outbreak without impacting the eventual number ill."

It's expensive and nearly impossible to seal off the borders of a country, the authors of the paper wrote. People will inevitably move — even indirectly from the countries that are quarantined.

(Spencer Platt /Getty Images)

4) Swine flu travel restrictions achieved exactly "no containment"

After the arrival of H1N1 swine flu in 2009, some countries imposed travel restrictions on flights going to and coming from Mexico, resulting in a 40 percent decrease in overall travel volume. A study looking at this event found it "only led to an average delay in the arrival of the infection in other countries (i.e. the first imported case) of less than three days." So again, reduced travel delayed (by three days!) but didn't stop disease spread.

The authors wrote: "No containment was achieved by such restrictions and the virus was able to reach pandemic proportions in a short time."

5) Airport screening after SARS didn't catch a single case

The US never adopted a travel ban in response to the 2003 outbreak of SARS, even though it was a much more infectious disease than Ebola. Still, a Canadian study of public-health measures to combat SARS found that airport screening was a waste of money and human resources: it didn’t pick up a single case of the disease. This screening was “inefficient and ineffective,” the authors of the assessment concluded, noting that Canadian public health officials should seriously rethink using it again in the future.

Even the equipment used to screen for flu didn’t work well. A study on thermal scanners for identifying travelers with influenza in airports found they were similarly useless when it came to stopping people with the flu from entering a country because of the high rate of false positives (raised body temperature isn’t always a good predictor of flu), and the fact that sick people might be asymptomatic. Passengers could also take a drug like acetaminophen (Tylenol) to lower their body temperatures and avoid detection. The authors concluded:

Governments may decide to implement entry screening, including [thermal scanners], for reasons other than to actually detect most influenza-infected arrivals, for example to deter unwell people from traveling, or to demonstrate to their citizens that they are doing everything they can to protect population health.

The risks associated with this approach include the potentially very large opportunity cost of further investigating [thermal scanner] ‘positive' travelers, including quarantine of those febrile on tympanic temperature measurement pending specimen processing, and the potential for the loss of public confidence in the pandemic response when it becomes clear that many infected travelers were not detected by the screening and entered the country.Travel restrictions are political theater

Travel restrictions are political theater

So not only does the evidence suggest travel bans won’t work, it doesn’t account for the devastating economic impact and potential harm to the Ebola aid response that such restrictions would bring about.

As Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, said during the last Ebola epidemic, “To completely seal off and don’t let planes in or out of the West African countries involved, then you could paradoxically make things much worse in the sense that you can’t get supplies in, you can’t get help in, you can’t get the kinds of things in there that we need to contain the epidemic.”

So are there alternatives? Instead of using airport screening and entertaining plans to seal borders, the governments of the world should focus their attention and resources on DRC, where the outbreak is out of control and where real action could actually be helpful in protecting America’s health security. We know this for sure: the longer Ebola rages on, the more people get the disease there, the more of a chance it has of spreading throughout Africa and the world.