The US and South Korea reported their first coronavirus cases on the same day.
South Korea’s total number of cases is higher than the US’ — the former has more than 8,300 while the latter has at least 6,400 — but the trajectories of those cases day by day reveals two different realities.
In South Korea, which instituted widespread testing, the number of new cases reported each day seems to be lower than the one prior — a sign the country has wrangled its outbreak. In the US, the number of new cases per day has increased steadily since March 5.
Two charts of new confirmed cases over time
For the month following South Korea’s first confirmed case, the number of cases reported there remained low.
Then the country saw a spike in late February, after a 61-year-old “super-spreader” infected many other members of a fringe religious group called the Shincheonji Church of Jesus.
Between February 20 and 29, the number of new cases reported jumped each day, peaking February 29 with 909 new cases.
Since then, South Korea’s daily case counts have decreased. On Monday, the country saw only 74 new cases reported.
The US’ epidemic curve started off looking similar to South Korea’s.
For the first month or so after the first confirmed case, the number of infected people remained low, with less than 15 cases.
Then, on February 28 — the day after the US’ first case of community spread — the number of cases started to rise each day, and that rise hasn’t stopped.
The US’ epidemic growth curve looks like a steep staircase, with each day bringing a new record number of new confirmed cases.
The US’ total number of confirmed cases is likely far lower than the reality because the country is still ramping up widespread testing. According to the COVID Tracking Project — a testing-tracking resource from two journalists at the Atlantic and the founder of a medical data startup — only 47,000 tests have been run in the US so far. (They note, however, that those figures may be incomplete due to different state policies on reporting negative tests.)
South Korea, by contrast, can test tens of thousands of people per day for COVID-19. As of Monday, the country had tested 274,504 people.
That allows them to quarantine infected people more immediately.
South Korea’s robust testing also likely means its confirmed case count is a more accurate representation of the number of cases in the country than the US’.