Since COVID-19, the disease caused by the novel coronavirus, first emerged in the Chinese city of Wuhan late last year, it has spread throughout the globe. But which countries have been hit hardest, and how has the outbreak developed over time?
The charts below compare timelines of the outbreaks in some of the worst-affected countries. “Day zero” in each country is set as the date on which the count of confirmed cases, compiled by researchers at Johns Hopkins University, passed 100. They will update on a daily basis. (Dates are defined in Coordinated Universal Time, which is four hours ahead of US Eastern Daylight Time.)
It’s important to realize that all these case numbers are inevitably undercounted, because no country is able to test everyone who might have the virus. And the extent of the undercount will vary from country to country, depending on how aggressively they have rolled out testing for people who have gotten sick. There may also be delays in reporting and compiling the data. And some governments have been reportedly covering up the true extent of their outbreaks.
The US health system was slow to start widespread testing for the coronavirus. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, told Congress on Mar. 12 that the US was “failing” on testing. South Korea, by contrast, launched a massive testing campaign once its outbreak took hold, catching a much greater proportion of cases than countries like the US, which reacted more sluggishly.
Deaths are likely to be counted more accurately than cases, which rely on how many people have been tested. This chart shows the number of deaths from COVID-19 in the same countries on the same timescale. As the pandemic continues, it is likely to provide a more reliable comparison of the severity of the outbreaks in different countries.
As the charts below show, the number of new cases in China — which placed the cities at the epicenter of the outbreak under strict quarantine in late January — seems to have slowed down since day 40.
Other nations are trying to repeat China’s success in “flattening the curve” of new infections, introducing measures including business closures and controls on travel. Keep checking on these charts to judge their success.