TORONTO -- The coronavirus has now spread to more than 170 countries and infected more than 1 million people worldwide, but a handful of isolated nations remain seemingly untouched by the pandemic -- for now.

According to global data compiled by Johns Hopkins University and first reported by the BBC, 18 countries of the 193 UN member nations have not reported a single case of COVID-19. Many of those countries are remote islands in the South Pacific, such as Samoa, Tonga and Vanuatu.

Experts believe that other coronavirus-free countries may be underreporting cases, including the notoriously cagey North Korea and conflict-ravaged Yemen.

It’s too early to say definitively whether or not the virus will spread to every last corner of the Earth. Harris Ali, a professor of sociology from York University who studied the spread of SARS and Ebola, said it’s possible that some nations will come away unscathed, but it isn’t likely.

“Nothing is remote anymore,” Ali told Friday in a phone interview.

Globalization has drawn inextricable links between global cities, which explains why the virus initially spread between tourists in large Asian cities before reaching Europe and North America. But even the smallest nations rely on some degree of international travel, be it for products or people.

“There will always be some connection with other countries somehow, some relative travelling, or the need for work, or tourists,” Ali said. “No place is an island itself.”

In hopes of mitigating an outbreak, the island nation of Nauru -- located about 4,300 kilometres from Australia with a population of 13,000 -- declared a state of emergency last month. So far, Nauru has reported zero cases, but the virus has already spread to nearby countries including Guam, Fiji and French Polynesia.

But there are several major unknowns with the coronavirus that may make keeping it out of countries like Nauru next to impossible. For instance, scientists still don’t know whether or not a second wave of the virus could happen in the fall or winter, as is the case with seasonal coronaviruses.

Preventing an outbreak would also mean that Nauru’s navy would need to limit all unauthorized travel -- something that York University professor Roger Keil points out is impossible for richer nations with tight border control, such as the United States.

“It is almost impossible in this scenario where any place in the world can shut themselves off hermetically to the current situation,” said Keil, a professor of environmental studies who also studied the spread of infectious diseases.

Keil described COVID-19 as the “first true global pandemic” because of how far and wide it has spread in a matter of four months. In his view, it’s more likely than not that the list of infected countries will grow.

"It has spread through cities and states in the most powerful countries in the world. There is no reason to believe it would not appear in those smaller places either,” he said.

North Korea has not officially reported any cases of the virus so far, but that does not mean the virus hasn’t taken hold. The isolated dictatorship is notoriously tight-lipped and, back in the 1990s, under-reported a famine that killed hundreds of thousands of people.

Andy Tatem, a professor in spatial demography and epidemiology at the University of Southampton, leads a mapping project out of the United Kingdom that helps China and other European countries track the spread of the coronavirus. When it comes to North Korea, he says the information is lacking.

“It's always hard to know what is happening there. I wouldn’t be surprised if they had it already and were not reporting. They are an isolated nation and there isn’t a whole lot of movement in and out. So it could be possible that they’ve avoided it, but my guess is there could be an outbreak there, given what’s happened in South Korea and the surrounding countries.”

And while a small number of countries have managed to stave off an outbreak, Tatem said he suspects that group will continue to shrink.

“I think it’s possible for these islands to completely shut up shop and put in place strict measures, and that might well stop them getting it. The other side of things is that the measures can be quite damaging to the countries in terms of stopping tourists that they rely on or stopping goods from coming in,” he said.

“This virus is going to be around for quite a while, so it’s hard to keep out and it’s damaging to keep up these lockdowns and quarantines. So it’s hard to know whether they will succeed in keeping it out forever.”