https://www.scientificamerican.com/article/why-daily-death-tolls-are-so-important-in-understanding-the-coronavirus-pandemic1/

COVID-19 is different from the viral epidemics of the recent past in a few ways: it is more widespread than severe acute respiratory syndrome, more infectious than seasonal influenza and has killed more people than Ebola.

And it is different in the way that epidemiologists are tracking its progress. Instead of relying principally on the number of infections, or the ratio of deaths to infections—known as the case fatality rate—researchers are looking at the daily deaths attributed to COVID-19 to monitor the impact of the disease and to guide responses.