This publication focuses primarily on restrictions on international movement by people seeking to take up long-term residence in a new country rather than short-term travelers, such as tourists or people on business trips. However, some of the points made also apply to the latter. This publication also does not examine the other nonpharmaceutical interventions that governments have enacted that may have reduced COVID-19’s spread or death toll, many of which may be correlated with different types of travel or migration restrictions. It will likely be years—if ever—before scholars understand how nonpharmaceutical interventions of all kinds, including migration and travel restrictions, affected COVID-19.

Pandemic-related migration restrictions have inflicted immense suffering on people fleeing violence, poverty, and oppression, including refugees escaping Cuba, Venezuela, and Haiti. Many of those barred under the Trump and Biden administrations’ Title 42 “public health” expulsions and other policies may be condemned to a lifetime of privation or even death. Pandemic-era migration restrictions have also cut off large numbers of people from job opportunities, contact with their families, and much else.

There is little doubt that COVID-19 is a genuinely dangerous public health threat. Millions have died in nations around the world. Travel bans have not done much to slow its spread, especially when there is already extensive “community spread” in the destination country. Then president Donald Trump’s imposition of the most severe immigration restrictions in all of U.S. history did not prevent COVID-19 from establishing itself in the United States and killing well over 800,000 people as of January 2022. Even pandemics such as the Black Death of the 14th century devastated the world in eras when the vast majority of people were peasants or serfs who rarely left the villages where they were born.

There is a kernel of truth to the idea that migration restrictions can stop the threat of contagious disease: if a nation or region could be hermetically sealed against virtually all entrants, then it could indeed prevent the introduction of any contagious disease. But in reality, such hermetic sealing is rarely if ever possible or desirable.

Any public health benefits of restricting migration must be weighed against the enormous costs—including slowing technological innovation that could help us combat future pandemics and other health threats. In the long run, immigration boosts innovations that make combating pandemics (and other health risks) easier. For example, the Moderna and Pfizer COVID-19 vaccines—the first two approved by U.S. regulatory authorities—were both developed by firms led by immigrants or children of immigrants from poor nations who probably could not have made their vital contributions to these medical breakthroughs had they or their parents been forced to live out their lives in their countries of origin. More generally, immigrants to the United States and Europe make disproportionate contributions to a variety of medical, scientific, and technological innovations, and present immigration restrictions block many additional advances.

Technological progress—including in medicine—would likely be much faster in the absence of current migration restrictions. Barriers to immigration to the United States are a particularly serious drag on scientific innovation because the United States has so many of the world’s top universities and research facilities. Immigrants to the United States account for some 20–33 percent of top “frontier knowledge” producers in science and mathematics—far more than migrants to other countries; reducing U.S. immigration restrictions could greatly accelerate scientific progress.

Australia managed to constrain the entry of COVID-19 with draconian immigration restrictions combined with harsh restrictions on internal freedom of movement and civil liberties. But even Australia failed to prevent the entry and spread of the Delta and Omicron variants.

In cases where migration restrictions can potentially slow the spread of disease, there are much more humane “keyhole” alternatives that are likely to be just as effective. Keyhole solutions are policies intended to mitigate potential negative effects of migration by means other than excluding migrants.

The most obvious keyhole solution is imposing a quarantine period on entrants, as was done in South Korea, which did far better at constraining COVID-19 than most Western nations that adopted travel bans. With quarantines, migrants can be isolated until it is clear that they do not have the virus or are no longer contagious. South Korea adopted a 14-day quarantine but did not bar migration and entry into the country. In December 2020, the U.S. Centers for Disease Control and Prevention (CDC) concluded that even a 7–10-day quarantine may be enough to guarantee against further spread of the disease. In December 2021, the CDC recommended that a five-day quarantine would be sufficient for people with asymptomatic cases and for those whose symptoms were resolving. If the five-day quarantine is sufficient, a shorter quarantine period for migrants might suffice too.

A 5‑, 10- or 14-day quarantine may be a deal-breaker for tourists or business travelers. But for most migrants, it is a small price to pay for the opportunity to live in a society that offers greater freedom and opportunity. The quarantine approach is likely to be far superior to exclusion of migrants as a tool for controlling public health risks. Unlike migration restrictions, the combination of free migration and the quarantine keyhole solution does not create a large population of undocumented migrants, who might have strong incentives to avoid vaccination and testing lest they come to the attention of authorities seeking to deport them. Such perverse incentives facilitate the spread of COVID-19 and other diseases. Migration detention facilities also often feature poor sanitation and facilitate the spread of COVID-19 and perhaps other diseases.

Effective COVID-19 vaccines also opened the possibility of an even better keyhole solution than quarantines: requiring vaccination as a condition of entry or a condition of eligibility for permanent residence as the United States has already done. Governments could offer vaccination to would-be migrants and grant permanent residency to those who accept. If necessary, the migrants could be required to pay for the vaccine doses from their future wages. The cost should not be high. A December 2020 media report indicated that the European Union had been paying vaccine manufacturers between about $2.20 and $18 per dose.

As with the quarantine keyhole solution, a border vaccination approach is likely to be more effective at controlling disease spread and preventing serious illness and death than a categorical ban on migration. Both keyhole policies would largely eliminate incentives for illegal migration and greatly reduce the danger of disease spread in migrant detention facilities. Both solutions also could potentially be adapted for use in future public health emergencies—though vaccination obviously only works in cases where there is a vaccine for the disease in question.

It is impossible to categorically rule out all scenarios featuring a deadly pandemic that can only be controlled by severe restrictions on migration rights. What we can conclude, however, is that there should at least be a strong presumption in favor of freedom of movement and that keyhole solutions such as vaccination or quarantine periods should be adopted in preference to categorical bans on migration.

It is also important to remember the enormous long-term benefits of freedom of movement for improvements in health care. Free migration increases scientific innovation, enables more people to enter the medical profession, and greatly improves health care outcomes over the long run. The analysis of migration restrictions is partly applicable to restrictions on other types of international travel, such as trips for business and tourism. These also have a dismal record of stopping the spread of viruses, as shown by their failure to seriously constrain the spread of the initial COVID-19 virus and later the more infectious Alpha and Beta variants. In November 2021, travel bans imposed by many governments against several nations in southern Africa predictably failed to prevent the spread of the Omicron variant. They have, however, inflicted great harm on many people and potentially imperiled future international cooperation in stopping the spread of COVID-19.

Restrictions on tourist travel inflict less long-term harm than migration restrictions since the former impose less of a global economic loss and are less likely to consign people to lives of poverty and oppression. They also pose less threat to long-term economic growth and scientific innovation.

Nonetheless, there should also be a strong presumption against restrictions on temporary travel. They also are unlikely to be effective and sometimes inflict severe harm on innocent people, such as those separated from sick or needy family members and those who lose out on valuable career opportunities.

In theory, governments could potentially impose very brief travel and migration bans when a potentially dangerous new variant is detected, just long enough to do some useful research and preparation or to temporarily assuage public fears until panic diminishes. Governments could then remove the ban once it no longer meaningfully constrains the spread of the disease. Governments also could let in “extra” migrants after a suspension of migration to make up for the reduction during the restriction period. That might, perhaps, work with well-informed “benevolent despot” governments, which are immune to political pressure and always scrupulously weigh costs and benefits. But wise benevolent despots are in short supply. In the real world, governments rarely have good information when a new disease or variant first emerges and rarely adopt the most targeted response.

And once instituted, travel bans and associated migration restrictions tend to remain for many months past the point where there is any chance they might do good. The bans instituted in response to the initial COVID-19 crisis remained long after both the original virus and later variants got in and achieved “community spread” throughout Europe and North America.

Political incentives kept them in place. For some on the right, the COVID-19 crisis was a good excuse to impose severe migration restrictions of a kind they had long advocated. On the left and center, many politicians feared to look “soft on COVID-19.” Prolonged border closures make it easier to send the signal that the government is taking a crisis seriously. Politicians and bureaucrats of all stripes are all too willing to inflict pain of a kind that disproportionately falls on recent immigrants, foreign workers, and their families—people with little or no political influence.

Similarly, there is little reason to expect that governments will take “extra” immigrants to make up for pandemic-era shortfalls. Certainly nothing of the kind has occurred in the United States or other nations that adopted severe migration restrictions during the COVID-19 crisis. Thus, pandemic-driven migration restrictions are likely to lead to permanent reductions in immigration that are not offset later. Indeed, there is a danger that some supposedly temporary migration restrictions might be perpetuated in the long run by anti-immigrant nationalists. Such dynamics might be less of a problem if voters were knowledgeable about border closures and related COVID-19 policies and effectively punished politicians who overstep. However, widespread public ignorance inhibits such monitoring here, as it does on many other policy issues.

Experience shows that migration and travel bans generally do little to constrain the spread of disease while inflicting severe harm on many people, especially vulnerable migrants and refugees. The evidence also suggests that governments cannot be trusted to impose travel and migration restrictions in a carefully calibrated way that maximizes potential benefits while minimizing harm. Thus, these tools should either be abolished entirely or subject to severe limitations. Particularly in the long run, such constraints are the best way to protect liberty, increase human welfare, and promote scientific innovation essential to improving health care.

This publication is in part adapted from Free to Move: Foot Voting, Migration, and Political Freedom (Oxford University Press, rev. ed. 2021) and Ilya Somin, “Here’s Why We Should End Pandemic Migration Restrictions,” The Hill, October 29, 2021.