​North Korea has taken some of the most drastic actions against the virus and did so sooner than most other nations. It sealed its borders in late January, shutting off business with neighboring China, which accounts for nine-tenths of its external trade. It clamped down on the smugglers who keep its thriving unofficial markets functioning. It quarantined all diplomats in Pyongyang for a month. ​The totalitarian state’s singular ability to control the movement of people​ also bolsters its disease-control efforts.

But decades of isolation and international sanctions have ravaged​ North Korea’s public health system, raising fears that ​it lacks the medical supplies to fight an outbreak, which many fear has already occurred…

Many observers of North Korea doubt its claims of not having any coronavirus cases. But a lack of testing ​equipment ​​may mean it literally has not detected a single case​, Dr. Park said​.

​”​It’s because they may have cases but they just don’t know how to detect it,” he said. “So they can say, ‘We have not confirmed it​.’”