Self-isolation.

Self-isolation was first adopted in March 2020 by African and South American countries (e.g., Benin, Bermuda, Ecuador, and Paraguay). Under self-isolation measures individuals are allowed to enter the country in line with standard immigration policy and advised to isolate themselves for a pre-defined period of time and not to have social contacts. They may be required to fill out a form saying where they intend to stay, and authorities have the right to check on that address. Most countries subsequently abandoned self-isolation and moved towards a complete shutdown of the borders. In April 2020, 11 countries used self-isolation as the only tool to limit the spread of the virus from other countries. In May 2020, self-isolation was introduced to complement more restrictive ‘no entry’ measures in 14 other countries. In such cases, self-isolation applied to individuals otherwise exempt from travel bans.

Quarantine.

Shortly after the World Health Organization (WHO) declared the COVID-19 pandemic on 11 March 2020, 25 countries introduced quarantine measures for international travellers. These measures allowed individuals to enter into the country in line with standard immigration policy but subjected them to mandatory quarantine in designated stations. With the increase of ‘no entry’ restrictions, 36 countries introduced the quarantine as a complementary measure, i.e., applied it to those who were exempt from the ‘no entry’ ban. Quarantine measures vary significantly in terms of the location and conditions of the facility (e.g., military barracks in Paraguay, five-star hotels in Cyprus), the length of isolation (e.g., 7 days in Slovenia, 21 days in the Central African Republic), and responsibilities for covering the costs (e.g., in Malaysia the government covers the costs for citizens but not for non-citizens).

Screening and testing.

Under the mandatory screening measure individuals are allowed to enter the country in line with standard immigration policy if they are granted clearance by health control at the border. They may be refused entry or placed in mandatory quarantine—i.e., their movement restricted—if they fail the screening. Controls range from simple measurement of body temperature to extensive symptom checks and swab sampling. This measure was used by eight countries in March 2020. It sharply declined in use when COVID-19 became a global pandemic, also as the WHO was not supportive of this measure (World Health Organization, 2020, p. 24). In May 2020, 16 countries introduced mandatory antibody testing upon arrival for individuals exempt from the entry ban. Such individuals are admitted in the country, but subject to follow-up measures in case of a positive test (self-isolation, quarantine, etc).

Medical certificate.

The requirement for individuals to provide a medical clearance ahead of travel was used by nine countries in the second half of March 2020. However, with the introduction of entry bans, medical certificate became obsolete. Throughout the months of April and May 2020, however, ten countries re-introduced a mandatory prior medical certification for travelers exempt from the entry ban.

Visa.

Twenty countries, mostly located in Asia and in the Middle East, suspended the issuing of all visas, or imposed pre-departure entry clearance that was not demanded before the outbreak of COVID-19. Eight countries abolished the visa requirement when they introduced the ‘no entry’ ban; 12 countries retained visa restrictions throughout the months of April and May 2020.

No entry.

The first blanket prohibition to enter a country was introduced on 24 January 2020 by the Marshall Islands, which issued travel restrictions for all persons travelling via air or sea from the People’s Republic of China [6]. No entry measures may apply selectively, to travelers from particular geographical locations, or they can limit all cross-border travel. The number of countries implementing a variation of a ‘no entry’ measure increased to 61 by 1 March 2020, 157 by 1 April, and 183 by 1 May. Our dataset shows regional diffusion patterns of this measure. In early March, most countries in Asia and in the Middle East introduced a ‘no entry’ ban. Between 13 March and 23 March 2020, there was a sharp increase in the use of the ‘no entry’ ban in Europe and the Americas. Travel restrictions, including closure of air and land borders, were put in place in late March 2020 in African countries.

Presence.

The measure concerns travelers who had been physically present in one of the affected countries in the 14 days preceding the date of travel. These restrictions are, by far, the most widespread. Many governments adjusted their targets as time went by. In early February 2020, presence-related restrictions targeted individuals who had travelled to or transited viral hubs such as Lombardy region in Italy, or Wuhan in China. By mid-March, such travel bans extended to entire countries. In many cases, the list of targeted countries changed over time. For example, in the initial proclamation of 11 March 2020, the US travel ban applied to individuals coming from Schengen countries [7]. It was revised on 14 March to include also Ireland and the United Kingdom [8], while Brazil was added to the list in late May [9].

Nationality.

In the early phases of the pandemic, twenty countries introduced ‘no entry’ restrictions based on nationality—a measure that may contravene article 12(4) of the International Covenant on Civil and Political Rights (ICCPR) guaranteeing readmission to nationals and settled residents–, applying to passport-holders of one of the affected countries. These measures also evolved over time. For instance, on 20 February 2020, the Russian government denied entry to Chinese nationals, unless in transit; on 28 February it banned the entry to all Iranian citizens; from 1 March South Korean nationals could only enter Russia via Sheremetyevo International Airport in Moscow; and from 13 March Russia denied entry to Italian citizens. A further example of a nationality ban is the case of Turkey, which denied entry to nationals of 69 countries regardless of their residence or previous stay. Overall, Chinese citizens have been the most frequent target of restrictions based on nationality. At the time of writing, Chinese with a passport issued in Hubei Province are still banned in Japan, South Korea, and Turkey.

Residence.

Restrictions targeting travelers who legally reside in one of the affected countries was used by six countries in the early stages of the pandemic. Throughout April and May 2020, the governments of Hong Kong, Lithuania, and the Marshall Islands retained restrictions based on residence in China, Italy, Iran, and South Korea.

Citizens and residents.

Article 12(4) of the ICCPR forbids arbitrary deprivation of the right to re-enter one’s own country. Most countries took a broad interpretation of this article, covering both the country of citizenship, and the country of residency in cases of permanent/long-term resident status. In fourteen countries, mainly in Asia and South America, only citizens were allowed to return. Some countries would not allow specific categories of residents to return. Indonesia and Japan denied re-admission to individuals without long-term residency status, Mongolia would not guarantee re-entry to residents without personal ties with nationals, and Curacao to those without specific government authorization. While these and other decisions are highly idiosyncratic, depending on the type of residency permits available in different countries, we still capture them. In particular, while we subsume all residency-related restrictions in the same category, we provide more detailed information on the exact nature of each restriction in the interactive visualization available online.

By contrast, in some cases both citizens and residents were denied entry into the country. The Maltese government set a deadline on 12 April 2020 for Maltese nationals and residents to return [10], while China put a travel restriction on all foreign nationals, including those who have a valid residency permit, starting from 3 April 2020 [11].

Family members.

A total of 21 governments allowed family members of nationals and settled residents to return to the country. In May, the governments of Denmark, Germany, and France inserted new provisions to allow nonmarried couples to cross the borders, as long as they could provide proof of “a stable relationship”.

Transport personnel.

In 39 countries goods transporters and commuters were exempt from travel bans. In the EU, they needed to show documentary proof of their right to cross the border.

Other categories.

Other exceptions include official delegations (54 exceptions), health care professionals and humanitarian workers (37 exceptions), international students (23 exceptions), individuals with a government authorization (21 exceptions), individuals with a temporary residence status (21 exceptions), and passengers in transit (20 exceptions). By contrast, asylum seekers (11 exceptions) and tourists (3 exceptions) were rarely allowed to cross international borders during the early phases of the pandemic.

In the Schengen Area, nationals of and residents in one of the 26 Schengen countries were frequently exempt from ‘no entry’ travel restrictions. Between early April and 1 July 2020, nationals of and residents in the Schengen area could transit through other countries to return to their country of nationality/residence.

Some countries allowed specific categories of workers (e.g., oil rig workers in Timor Leste), organized dedicated travel corridors (e.g., fruit pickers in the United Kingdom), or introduced exceptions to the closure of the borders (e.g., the border between Switzerland and Italy remained open to trans-border workers). In May 2020, only 12 countries granted an explicit exception for all individuals with a work authorization to cross the national border.