The first action the U.S. government took to combat the spread of COVID-19 was a travel restriction on people who had been in China in the previous two weeks prior to their attempted entry. That order exempted people closely related to Americans on lesser visas, returning American tourists, and some others, but it “pretty much shut it down coming in from China,” as President Trump said.

Travel and immigration restrictions should be enacted if they halt or substantially diminish the spread of deadly and contagious diseases, but the only problem is that they aren’t effective. Travel and immigration restrictions likely did not delay the prevalence of COVID-19, delaying the disease’s spread by 15 days at most.

A new Cato Working Paper lays out our findings. Beginning in late January, we tracked the number of COVID-19 cases in the United States and 13 other countries in the Northern Hemisphere that did not have strict bans on travel and immigration from China. We ran eight different simulations based on real-world data to see what would have happened to the U.S. without travel and immigration restrictions on China. We then compared those counterfactuals to what really happened. In six simulations, after the U.S. travel restriction was enacted, United States COVID-19 cases increased similarly to what really happened.

One of our eight simulations did find that the U.S. travel and immigration restrictions delayed the spread of COVID-19 domestically for about 15 days, to February 17th, but then U.S. cases caught up with those in other countries without a travel and immigration ban. In short, the U.S. travel and immigration restrictions performed dismally in all simulations.

This isn’t a surprising finding and it’s not unique to COVID-19.

Strict quarantines, akin to travel and immigration restrictions, put in place a century ago to combat the Spanish Flu were only effective in insolated islands and Australia. Restrictions in the latter case delayed the spread of Spanish Flu for three months compared to New Zealand that had no restrictions. Some South Pacific islands with strict quarantines and restrictions, as well as Madagascar, either escaped the Spanish Flu entirely or delayed its arrival by years. But that was prior to the age of international air travel.

Land border closures to combat the Spanish Flu were ineffective. Liberia and the African colonies of Gabon and Ghana had quarantines at their land borders that might have delayed the spread of Spanish Flu by a week or two, but the data don’t tell us much. Australia tried to restrict travel between its states to limit the spread of the disease but it had no effect and Australian authorities soon abandoned the effort. Ditto for Canada when it tried to restrict movement between its provinces. 

During the 1957 flu pandemic, the onset of the disease in Israel was delayed two months relative to its neighbors due to security restrictions on movement between warring countries. South Africa delayed the arrival of some ships to port, but there is little to no evidence that it had an effect. Writing about travel restrictions, World Health Organization experts wrote that “no effect was detected. It seems that if such measures are to be effective, they must be very severe … a high price to pay for a few additional weeks freedom from the disease.”

The big problem is that governments typically impose international travel restrictions after the pandemic has spread internationally. At that point, travel and immigration restrictions are akin to pulling the fire alarm after the building has burned down.

That mirrors the current situation. The first known case of COVID-19 in the United States came from a traveler who arrived on January 13, more than two weeks before Trump imposed the China travel and immigration restriction. And COVID-19 likely had been seeded in dozens of other countries at the time that were not subject to a U.S. travel or immigration restriction. On average, the Trump administration waited 18 days after the first confirmed case of COVID-19 in a country to impose travel restrictions on travelers and immigrants from there, according to my colleague David Bier.

It’s tempting to say that more travel and immigration bans earlier would have helped. But in the real relying on travel and immigration restrictions to halt or slow the spread of the disease is a fool’s errand and might even distract from more effective measures by imposing a false sense of security.

States across America are lifting some of their shelter-in-place orders, while others are debating doing so. Soon, we’ll be debating whether and how to reopen the immigration system. The evidence shows that international travel and immigration restrictions were ineffective at stopping the spread of COVID-19. At a minimum, we should consider reopening those systems too.