This graph shows the number of daily
reported cases of COVID-19 for 10 countries.
While some countries have been able to flatten the curve,
others have seen exponential growth.
Even when adjusted for population,
some of these curves look very different.
Reports have attributed these differences
to three key factors:
isolating cases, testing, and tracing cases.
So to better understand how each measure affects the curve,
we decided to compare these four countries
and their different responses.
Why does South Korea have a bell curve
while the US has a steep slope?
Let's zoom in, starting with China,
the first country to be hit by the virus.
Here's China's curve,
but the crisis started well before these numbers peaked.
On December 31,
China reported to the World Health Organization
that it was treating dozens of cases of pneumonia.
A week later, a new type of coronavirus was identified,
and the genome was mapped.
Later that month, China isolated Wuhan,
the city where the virus was thought to have originated.
A lockdown was then expanded to 36 million people.
And during that time,
China was building emergency hospitals
and developing a rapid testing kit.
By mid-February, over 700 million people
were placed under travel restrictions or quarantine.
And by the end of March,
China had conducted over 320,000 coronavirus tests
and had attempted to trace each of the 80,000-plus cases.
After a large outbreak, it was able to flatten the curve
to the point where, earlier this month,
China reopened Wuhan,
over 10 weeks after the lockdown started
and over 13 weeks after the first cases were reported.
Its curve is unique, though,
because it was the first country to deal with the virus,
and the lack of public information and measures early on
allowed the virus to spread.
The eventual lockdown measures it took
were particularly drastic, but in the meantime,
the virus spread to other countries.
One country in particular
has a curve that looks different than most.
South Korea started developing COVID-19 tests
before its first confirmed case.
The country had put procedures in place
for managing an outbreak after dealing with MERS in 2015,
and it had a testing methodology ready
even before the new coronavirus was identified.
By early February,
South Korea's first test has been approved,
and it used extensive contact tracing
to identify the travel of each confirmed case,
down to details like a person's seat number
or what stop they got off the bus at.
The data was anonymously posted online
so people could check if they came in contact
with a confirmed case.
This became an important part of its strategy.
Not only was it testing aggressively,
but it was also contact tracing.
Anyone who was thought to be infected
could then be tested and isolated.
A month later, cases peaked,
but over 100,000 people had already been tested.
By late March, South Korea had tested three times that,
and a social-distancing order banned large gatherings,
further slowing the spread of the virus.
Some experts say that by developing broad testing
and contact-tracing measures
before its number of cases spiked,
South Korea was able to flatten the curve.
The country is still reporting new cases,
but compared to the over 900 daily cases during its peak,
the outbreak is much more manageable.
And social-distancing measures are still in place,
further limiting the spread of the virus.
Let's look at Germany next.
It had a test ready by mid-January.
Four days later, Germany had its first confirmed case.
It was able to start manufacturing tests by early February,
allowing it to test about 120,000 people per week
by early March,
and it implemented several social-distancing measures
later that month,
closing schools, borders,
and banning gatherings of more than two people.
By late March, Germany was testing
over 300,000 people per week.
As of April 8, Germany had tested more people
than any other European country.
This is due in part to its early testing
and its use of contact tracing,
which allowed testing to identify
even the mildest cases of COVID-19.
But case numbers have been high.
As of April 10,
Germany had the fifth-highest number of COVID-19 cases,
but it has one of the lowest fatality rates in the world.
Some experts think that Germany's expansive testing
has kept the fatality rate so low.
But not every country was able to start testing early.
The US currently has the highest number of confirmed
COVID-19 cases in the world.
Its first case was confirmed on January 21.
And while we don't start to see a spike until March,
that doesn't mean there weren't cases before that.
They likely went undetected due to a lack of testing.
According to the Associated Press,
US government labs processed only 352 COVID-19 tests
in all of February.
Testing only ramped up in early March,
when the CDC started to allow private companies
to develop their own tests.
But for a while, tests were only available
for people who had traveled from China
or had a fever severe enough to be hospitalized,
and the lack of contact tracing, quarantine,
or physical-distancing measures exasperated the spread.
By March 11, over 100 colleges
had canceled in-person classes,
but major social-distancing steps didn't take place
until mid to late March.
Almost two months after its first case,
a national emergency was declared.
The White House and the CDC
advised against large gatherings,
and states like California and New York
issued stay-at-home orders.
But by then, the US was already seeing
over 10,000 cases per day.
Now over 40 states have stay-at-home orders in place.
But the US has been criticized
for not implementing preventative measures early.
It was slow to gather resources
while the virus was spreading to other countries,
and a botched rollout
meant that testing didn't start to expand until mid-March.
With little testing and hardly any contact tracing,
the virus was able to spread silently
throughout the country.
The US is now testing over 100,000 people per day.
But as of April 13,
the US still had fewer tests per 1,000 people
than South Korea.
An earlier start in identifying and isolating cases
could have prevented such a large outbreak.
In many countries, it's not just one measure
that flattens the curve.
It's the combination of isolating, testing, and tracing.
Countries that have been able to do all three swiftly
have been able to lower their number of new cases,
but those that haven't will likely take longer
to flatten the curve.