As I write this, on March 29, 2020, according to the World Health Organization, there have been 634,835 confirmed cases of Covid-19, the disease caused by the SARS-CoV-2 virus, leading to 29,891 deaths. In the USA, there have been 103,321 confirmed cases and 1,668 deaths. In the coming weeks, even with the quarantines and shelter-in-place orders—the effects of which will take weeks to be seen—these figures are going to look tiny.
Since worldwide testing has tended to have been directed at those with severe symptoms, it’s not known with great accuracy what the true mortality rate is, that’s the rate that people who become infected with the SARS-CoCV-2 virus end up dying from the infection. However, a reasonable estimate now places it somewhere between 0.5 and 1%. Some estimates are even lower than 0.5%.
Our measurement of the number of people who have died is clearly much more accurate than our measurement of the number of people who have been infected. With the lowest estimated mortality rate of 0.5%, we can generate a potentially more accurate assessment of the number current infections: 5,978,200 worldwide (almost ten times the confirmed number) and 333,600 in the USA (over three times the confirmed number).
You might protest that 0.5% is underestimating the mortality rate. Okay, so let’s use the estimated upper bound of 1%. That yields…
