How lethal is the novel coronavirus, and how many undetected cases there are? The importance of being tested.

Ugo Bastolla

in the exponential phase (here d 0 = 0.012, so the first factor is estimated to be 82f that is probably larger than 1 depending on f ). Note that this expression does not depend on t. However, both t d and t r are expected to depend on the age group so that t d decreases for older people and t r increases. We hypothesize that, in the initial stage, the deaths tend to affect younger persons, who travel more and have more social contacts, while at a later stage they affect more the elders, while people that recover tend to be of the same age throughout the epidemics. These assumptions imply that t d − t r decreases with time, producing the observed exponential decrease of R(t)/D(t), until the age distribution of people that die and recover becomes stationary. At this point R/D becomes approximately constant in the exponential phase, as observed in Fig.5 in the curves from Italy and Spain. Data to test the above hypotheses should be available.