Well you have to know how many are infected vs how many die to get the mortality rate.
The death rate for the flu is believed to be around .01%, where as the death rate for Coronavirus is believed to be anywhere between 1% and 3%
The flu epidemic of 1918 only attacked the elderly and young in the first wave. In the second wave it mutated and was much harder to fight. It affected 1/3 the earths population and had a 3% mortality rate. Lets hope history doesnt repeat itself