But in South Korea, people are starting to come back out on the streets.

Starting in late February, South Korea was reporting a sharp increase in coronavirus cases.

With over 5,000 infected, they were registering some of the highest numbers of confirmed cases in the world.

But then something changed.

While cases in most other countries continued to rise, Korea's numbers started leveling off.

Look at how this curve starts to bend.

It indicates that Korea managed to contain the spread of the virus early on.

And they were able to do it because they'd learned a valuable lesson a few years ago,

when they fought a different coronavirus outbreak.

In South Korea, the Middle East Respiratory Syndrome.

The death toll, on the rise.

Aggressively trying to contain the deadly outbreak.

The government was caught completely off guard.

Authorities are still trying to track down and isolate anyone who may have been exposed.

In 2015 a Korean businessman returning from the Middle East developed a fever, cough, and eventually pneumonia.

He went to several health facilities for a diagnosis,

before finally testing positive for MERS or Middle East Respiratory Syndrome caused by a coronavirus.

By that point his movements had created a chain of transmission that became hard for officials to trace.

They didn't know who was infected or where they had been.

Altogether, the virus infected 186 people

and killed 38 in South Korea.

The highest of anywhere outside the Middle East.

The government declared an end to the outbreak in 2015.

But they didn't stop planning.

The lessons all came into play when the next outbreak took hold in the country.

On December 31st, 2019, China reported the first case of the coronavirus.

In the following weeks, as the outbreak started spreading across the world, South Korea only had 30 confirmed cases of the virus.

But despite the low numbers, health authorities had already started working with biotech companies to develop a test for the novel coronavirus.

And soon, they had thousands of test kits ready to go.

They prepared for the worst, and the worst quickly followed.

By late February, the total number of coronavirus cases rose dramatically, crossing 3000.

This made South Korea's outbreak the largest outside of mainland China.

And it all started here in Daegu, where a woman went to the hospital with a fever.

Because the government had already equipped hospitals with coronavirus tests, doctors were able to test her.

She tested positive and became known as patient 31.

But the testing didn't stop there.

While she was sick, patient 31, had gone to a megachurch where she sat with a congregation

of hundreds for more than an hour.

So they traced her movements, identified people

she had come into contact with

and tested those people as well,

whether they showed symptoms or not.

Many of them also tested positive.

So they were quickly isolated and treated at home or at a center.

And then, all the people they had been in contact with were traced and tested too.

This is called contact tracing.

It's an approach that allowed Korea to test over 9,000 people who had been in contact with someone who had tested positive.

After Daegu, Korea ramped up testing around the country.

Private and national healthcare systems joined forces to set up a mostly free testing effort

that includes more than 600 locations that screen as many as 20,000 people per day.

Through this system, when anyone tests positive, the government is able to test and trace their contacts

to continue to break the transmission chains of the coronavirus on a large scale.

But that's just the human to human transmission, the infected person may have moved through the city,

touching subway poles and door handles.

And South Korea had prepared for this too.

After the MERS outbreak, when they weren't able to trace the movements of the virus,

Korea changed the law allowing the government to collect a patient's data and security

footage during an outbreak.

All their steps are logged and then shared

to alert people to stay away from the path of infection.

Websites and private apps compile the information allowing everyone to see if a person with

a confirmed case of coronavirus went to a pharmacy or the hospital, or anywhere else.

And they'll know how recently they went too.

It's a means of checking the possibility of infection.

Citizens are checking the coronavirus locations and are avoiding going to these areas.

This information lets people know if they've crossed paths with an infected person so they

can go get tested for the virus.

And contact tracing starts all over again.

Tracing people's every move can be controversial but many in South Korea prioritize public health over privacy in an outbreak.

As a result, South Korea was able to test hundreds of thousands of people,

more than any other country at the time.

And this made it easier for authorities to see the virus.

To see where it's located and where it may be lurking.

This ability to find and treat infected people has allowed Korea to avoid aggressive lockdowns.

And it's helped bend the curve of the outbreak that started out dangerously steep.

For now, Korea has turned a corner, but they continue to be prepared.

It's that kind of vigilance that has set Korea apart in the coronavirus pandemic.

But it wasn't the only place to test people aggressively.

Singapore, Taiwan, and other neighbors saw the benefits of widespread testing too.

Now countries like Germany and the UK are starting to implement aggressive testing.

And even the US, where the government has failed to provide adequate testing, is now

scrambling to test more people.

We know that we have to do more

and we continue to accelerate in testing.

Korea's strategy of contact tracing might not be easy to replicate in countries with much larger populations.

But the country's success with widespread testing,

still offers a way out for most countries

that are stuck in lockdowns.