Japan was one of the first countries outside of China hit by the coronavirus and now it's one of the least-affected among developed nations. That's puzzling health experts.

Unlike China's draconian isolation measures, the mass quarantine in much of Europe and big U.S. cities ordering people to shelter in place, Japan has imposed no lockdown. While there have been disruptions caused by school closures, life continues as normal for much of the population. Tokyo rush-hour trains are still packed and restaurants remain open.

The looming question is whether Japan has dodged a bullet or is about to be hit. The government contends it has been aggressive in identifying clusters and containing the spread, which makes its overall and per capita number for infections among the lowest among developed economies. Critics argue Japan has been lax in testing, perhaps looking to keep the infection numbers low as it's set to host the Olympics in Tokyo in July.