> during the first half of an epidemic, when a small portion of the population is infected and infections are growing exponentially, it makes sense to use the a

> during the first half of an epidemic, when a small portion of the population is infected and infections are growing exponentially, it makes sense to use the absolute number of infections. That's even a bit of an understatement, because three infected in a city of millions can easily be an early stage pandemic whereas three infected in the middle of nowhere would just be a three very unlucky persons.