How deadly is the new coronavirus?
AS THE NUMBER of deaths among people infected by the new coronavirus mounts, it is tempting to divide that figure by the number of reported cases and conclude that the result is the fatality rate. Apply such maths to the world’s total of confirmed cases and deaths on March 11th and you get a fatality rate of 3.6%. But this figure, which epidemiologists call the “naive” case fatality rate, may be wrong in two different ways.