The Seoul government was able to slow the spread of coronavirus and limit deaths. What did it do right? Here's everything you need to know:

How does South Korea compare with the U.S.?
Both countries saw their first corona­virus cases on the same day, Jan. 20. By April 2, the U.S. had more than 240,000 cases and more than 5,800 deaths. Most businesses were shut down or crippled, and more than 10 million people had filed for unemployment in two weeks. In contrast, South Korea on April 2 had fewer than 10,000 confirmed cases and 169 deaths. The disease rate there appears to be both low and stable, yet no South Korean city has gone under a full lockdown, and the main economic losses were in the tourism industry. Few people lost their jobs. The difference is that South Korea sprang into action with early mass testing, tracking and isolating all contacts of those infected. It started developing and stockpiling test kits in early January, as soon as Chinese scientists released the virus's genetic code and before a single Korean had been infected.

How did they know to do that?
An outbreak of Middle East Respiratory Syndrome (MERS) in South Korea in 2015 exposed vulnerabilities that terrified the populace and forced an overhaul of epidemic response. A single patient infected with MERS — caused by a different coronavirus than the one that causes COVID-19 — brought it in from the Middle East, was treated at three hospitals, and sparked outbreaks in each one, infecting 186 people and killing 38. That epidemic was quashed in two months by quarantining nearly 17,000 people, but the experience badly damaged the popularity of then–President Park Geun-hye. Seoul drew up new rules for health ­crises, empowering the Korea Centers for Disease Control and Prevention to take full authority to direct local responses. And social norms established during MERS made the population willingly adopt mask wearing in public. South Koreans learned that because any new virus can spread exponentially, stamping out each new outbreak quickly is the key to avoiding catastrophic growth.

How did they react this time?
Just three days after news broke on Dec. 31 of a novel pneumonia in Wuhan, China, the KCDC set up a response team to study the virus. Once the first case appeared, authorities started tracking the health of some 3,000 people who had traveled to Wuhan over the previous two weeks. The KCDC assembled a vast public-private network to produce and administer tests, including drive-through centers, and established labs to process them. The cases that had come from China were largely contained — but then in mid-­February, a "super-spreader" was identified in Daegu, the third-­biggest city, who had infected hundreds of people at several services at the Shincheonji Church of Jesus. Over 10 days, cases soared from fewer than 50 to more than 5,000. South Korea quickly surged its testing to some 20,000 people a day, but it also took more extreme measures.

What were these?
President Moon Jae-in allowed the use of invasive surveillance tactics to track worshippers at Shincheonji churches across the country. South Korea's phone companies have each user's national ID number. So authorities were able to follow the movements of infected people and identify those they had interacted with over the past 14 days. Those contacts were then told to self-isolate and report their temperatures daily. Their compliance was voluntary, but South Koreans know the government can monitor their movements through phone data and an extensive CCTV network of 8 million cameras. Anyone who tested positive was sent to one of the quarantine centers set up in hotels and company dorms. After one worker at an insurance company in Seoul tested positive, authorities set up a tent to test everyone in the building.

Did other countries follow suit?
The other Asian countries with effective responses to the pandemic are Singapore, Vietnam, and Taiwan. All were previously hit by the 2003 epidemic of another coronavirus, severe acute respiratory syndrome (SARS), which had a terrifying 10 percent fatality rate. Because of swift measures in affected areas, it killed just 774 people. In the aftermath, all three countries adopted new health policies involving mask wearing, testing, and tracking. When COVID-19 hit, populations in those countries had masks at home, and high enough levels of social trust to quickly obey government orders to report for testing and stay at home. Taiwan has had just five deaths from COVID-19; Singapore has had six. "The situation in [Western] countries now resembles the situation we were in during the first few weeks of the SARS spread in Taiwan in early 2003," Su Ih-jen of Taiwan's CDC told the Financial Times. "You are not ready, you have no experience."

What the U.S. can do
The Trump administration's failure to test and impose distancing rules for two months let the virus gain a foothold and led to the current exponential increase in cases. But it's not too late to implement much wider testing. South Korea has tested 1 in every 119 of its people. The U.S. says it has performed 1.2 million tests, but since each patient is given at least two tests, that works out to fewer than 1 in 500 Americans. Most Americans who suspected they were infected have not been able to get tested. At this point, with more than 300,000 known infections and probably far more, tracking contacts will be impossible. "To try to do contact tracing on thousands on thousands of people is like trying to do the census in a couple hours," says Michael Osterholm of the University of Minnesota's Center for Infectious Disease Research and Policy. And the U.S.'s culture of individualism and states' rights make it unsuited to extensive contact tracing, surveillance of infected people, and other extreme measures. Governors in eight states were still resisting pleas this week by federal health officials that they issue mandatory stay-at-home orders, citing fears of infringing on "personal liberty." Even when he finally surrendered to pressure, Florida Gov. Ron DeSantis — who earlier allowed spring breakers to party on beaches for weeks — exempted religious services. "I don't think that the government has the authority to close a church," DeSantis said.

This article was first published in the latest issue of The Week magazine. If you want to read more like it, try the magazine for a month here.