Tracking COVID-19 cases and deaths

Early mass testing and early containment measures save lives.

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This post provides up-to-date data beyond that included in Humanity tested and Sustained suppression.

[Data updated on Wednesday May 27. Graphs were revamped on April 27; since then some data errors have been corrected and new countries have been added.]

Insights from the data:

  • Most highly affected countries and subnational regions have turned the corner in confirmed cases, and some in confirmed cases and deaths. However, the way down is much slower than the way up (and much slower than for China's decrease after their peak).
  • South Korea and China have been most successful at limiting the spread of the outbreak and at bringing their confirmed cases and deaths down. Smaller countries such as Singapore, Taiwan, New Zealand and others have also been successful, with cumulative deaths around 10 (or below it, in which case the country does not appear in the graphs).
  • As a general trend, countries running a larger number of tests per capita and those who have locked down earlier, show 'flatter' curves (with respect to the straight lines of constant case fatality rates) and have fewer total deaths. (Demographics and the capacity of the healthcare system also matter, though.)
  • Countries with low levels of testing may be missing a large number of cases and deaths, as these need to be confirmed by testing for the virus' RNA. For example, for Ecuador, an analysis by The New York Times suggests that country's death toll is 15 times higher than reported. That is, testing levels set a cap to the number of cases that can be detected. However, how the numbers change over time should be a more reliable indicator of progress than the actual numbers themselves.
  • 'Kinks' and 'zig-zags' in the trend lines largely arise from reporting inconsistencies, such as large numbers of previously unreported cases and/or deaths reported in a single day.

COVID-19 confirmed cases and deaths for selected countries in a 14-day window ending at each data point (successive data points on a line denote consecutive days). Numbers in colour are the approximate number of total PCR (polymerase chain reaction) tests per million people up to the data point indicated. Stars indicate when strict lockdowns were enacted. 

Deaths lag with respect to confirmed cases, as indicated by the estimated two–to-three weeks interval between the onset of symptoms and death. Case fatality rates — that is, the fractions of total confirmed cases that have become deaths — mostly depend on the extend of testing, on the capacity of a country’s healthcare system, on its demographics, and on the availability of drugs that can significantly dampen the severity of COVID-19 in those infected. The case fatality rate of COVID-19 is expected to be a multiple of that for seasonal flu in the United States (0.1%).

Countries that deployed tests for detecting SARS-CoV-2 RNA early and widely (such as South Korea), that applied contact tracing and targeted physical distancing measures for detected cases (such as South Korea and Japan), or that enacted early strict lockdowns (such as China) are more likely to contain the disease outbreak earlier. In fact, Singapore, Hong Kong and Taiwan have contained COVID-19 outbreaks, and manage to limit COVID-19-related deaths to less than 10 (hence, these countries are not included in the figure). 

Individual data points can be affected by reporting errors and delays, by wilful underreporting, and by location-specific definitions (and changes to them) for confirmed cases and COVID-19 related deaths.

Data sources: European Center for Disease Control and Prevention (cases and deaths); Our World in Data, various government sources (tests).

Below are similar graphs, for total confirmed cases and total deaths (rather than for 14-day rolling numbers).

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Pep Pàmies

Chief Editor, Nature Biomedical Engineering, Nature Research

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