On 31 December, 2019, the World Health Organization was first notified of an outbreak of pneumonia in Wuhan City, China. Less than a month later, WHO Director Dr. Tedros Adhanom Ghebreyesus declared the new coronavirus, called COVID-19, a public health emergency of international concern.
The number of cases reported in a country is highly dependent on several factors, such as the rate at which people are tested for the virus. However, monitoring country cases (and the rate at which they change) are an important glimpse into the pandemic’s trajectory. Additionally, as a metric for the rate of change in each country's epidemic, we display the five-day proportional increase in the number of diagnosed cases.
We also display the number of reported cases, relative to the number of COVID-19 related deaths. This metric is dependent on two factors: the number of tests performed in each country and the likelihood of identifying whether a person died due to the infection (as nicely shown in this piece in The New York Times).
As such, this ratio is not necessarily related to the case fatality rate; it does, however, provide insight into each country's response. A low ratio, such as 25, means that for every one person who has died from COVID-19, only 25 others were diagnosed with the virus. If the virus is thought to kill about 1% of those infected, such a country is likely failing to diagnose about three-quarters of those actually infected. Unusually high fatality rates, such as when health systems become overwhelmed, can also drive down this ratio.
Top fifteen countries by number of diagnosed COVID-19 cases
We also compare the trajectory of diagnosed cases over time, starting from the date when each country diagnosed its 100th patient. Again, this graphic doesn't necessarily display the actual epidemiological trajectory of COVID-19, since it is so dependent on testing rates.
Number of reported cases, by day since 100th diagnosed case
Since about one in five people that contract COVID-19 may require inpatient care, some for many weeks, the ability for national healthcare systems to absorb patients is critically important. In China, hospitals were built in just days to accommodate patients. By contrast, Italian hospitals have become overwhelmed by the rapidly increasing number of patients requiring care.
As an indicator for national health system capacity, we plot the number of hospital beds per 1,000 people against the cumulative COVID-19 death rate. Of course, this metric does not take into account any other important healthcare characteristics, such as rates of under- or un-insurance, costs of healthcare, accessibility of facilities (such as to rural communities), and quality of care.
Hospital beds per 1,000 and COVID-19 deaths per million
There is currently no vaccine that protects against COVID-19. According to the U.S. Centers for Disease Control and Prevention, the best ways to prevent transmission of the virus is to stay home if you are ill or think you may be ill, cover your sneeze and wash your hands often, and avoiding touching your face. The CDC now recommends that people wear cloth face coverings in public places.
Cumulative confirmed cases and deaths, by U.S. state
