Just a couple of months ago, the world was enjoying greater freedom of movement than at any time in history.

Air traffic had been rising steadily for decades. The Henley Passport Index, which measures the world's most travel-friendly passports, announced in January that Japan had topped its 2020 ranking, with its citizens able to visit a record-breaking 191 destinations without requiring a visa in advance.

Worldwide, citizens were enjoying visa-free or visa-on-arrival access to 107 destinations on average -- almost double the 58 destinations that were open to the average traveller when the index started in 2006.

But today, with 93 per cent of the world's population living in countries with coronavirus travel bans, the playing field has been temporarily levelled.

Having lost the freedom of movement we once took for granted, what are the long and short-term impacts for passport power in 2020 and beyond?

CNN Travel spoke exclusively with Christian Kälin, creator of the Henley Passport Index, who is sometimes known as "The Passport King."

Asia in the lead

"It's a very simple measure," says Kälin of the index, which is based on data provided by the International Air Transport Authority (IATA) and covers 199 passports and 227 travel destinations. "It's a broad reflection of geopolitical relationships and a measure of openness of countries."

Japan has held onto its position at the top of the leaderboard as we enter the second quarter of 2020, Singapore in second place, and Germany and South Korea tied for third.

Luxembourg and Spain join Italy and Finland in fourth place, while Austria has risen to join Denmark in fifth. The index is updated in real time throughout the year, as and when visa policy changes come into effect.

However, the unprecedented circumstances of the novel coronavirus outbreak has, in some cases, turned passport power on its head.

"Look at Spain, or any other country which has a complete lockdown. Before, as a Spanish citizen you had one of the best passports in the world in terms of free travel," explains Kälin. "Now, if you were also a Bangladeshi citizen -- normally a very bad passport for visa-free travel -- you could freely go out to the airport and board a flight, if you find one, and leave Spain."

Health security

It's Kalin's view that the pandemic won't have a long-term impact on the passport index, and that things are likely to return to more or less normal.

However, "if you look at this current crisis, aspects of health -- the quality of health system, the quality of emergency care, access to health cover and healthy service -- suddenly have come up. That has never been a consideration on visa policy so far."

While policy is usually guided by "questions of mostly economic and geopolitical standing of the country," it will be interesting, says Kalin, to see whether health security will in future be a bigger factor when it comes to visa waivers.

Kalin says it's worth noting that the passport index is an effective but crude tool in comparing geopolitical clout. The United States is more attractive as a business and leisure destination than North Korea, for example, but the index ranks visa-free access to each as being of equal value.

He says that the Quality of Nationality Index, which he also developed, is "much more sophisticated" with an "elaborate methodology" which covers GDP, human development, internal peace and settlement rights.

Performance is relative

Japan is at No. 1 in the Passport Index and the United States at No.7, but the Quality of Nationality Index places them at No. 26 and No. 25 respectively.

"Japan's a great country, but you can only live in Japan," explains Kalin. "With the U.S. passport you can only really live in the United States. You even need a settlement permit to go to Canada."

Compare that to the generous settlement rights enjoyed by citizens in the European Union, or the 15 countries which make up the Caribbean Community.

As for the repercussions of Brexit for the United Kingdom, "there will probably be not be much change" on the Passport Index, says Kalin, "because you will still be able to go on holiday to Spain.

"But on the Quality of Nationality Index, Britain will probably lose significantly. Suddenly you can't just settle in Spain [if you hold a British passport], you need a permit."

'Beyond our control'

Ireland is just one place above the U.K. on the Passport Index, at No 6. However, a record-breaking 900,000 Irish passports were issued in 2019, due to a steady rise in applicants from British residents since the Brexit vote in 2016.

That surge can be attributed to the desirability of the freedom of movement afforded by being an EU citizen. "In terms of passport power, Ireland is remaining similar to the U.K., but in terms of quality of nationality, Ireland is suddenly better," explains Kalin.

Said Kalin in a press release today, "The last few weeks have made it apparent that travel freedom is contingent on factors that occasionally can be utterly beyond our control.

"As public health concerns and security rightfully take precedence over all else now, this is an opportunity to reflect on what freedom of movement and citizenship essentially mean for those of us who have perhaps taken them for granted in the past."

The best passports to hold in 2020 are:

1. Japan (191 destinations)

2. Singapore (190)

3. South Korea, Germany (189)

4. Italy, Finland, Spain, Luxembourg (188)

5. Denmark, Austria (187)

6. Sweden, France, Ireland, Netherlands, Portugal (186)

7. United States, United Kingdom, Belgium, Norway, Switzerland (185)

8. Czech Republic, Greece, Malta, New Zealand (184)

9. Canada, Australia (183)

10. Hungary (182)

Other indexes

Henley & Partners' list is one of several indexes created by financial firms to rank global passports according to the access they provide to their citizens.

Arton Capital's Passport Index takes into consideration the passports of 193 United Nations member countries and six territories -- ROC Taiwan, Macau (SAR China), Hong Kong (SAR China), Kosovo, Palestinian Territory and the Vatican. Territories annexed to other countries are excluded.

Its 2020 index puts the UAE on top with a "visa-free score" of 178, followed by Germany, Finland, Luxembourg and Spain with 171.