Mortality and R0 will be inversely correlated viruses that excel at killing the host will be contained by the hosts dying rather than infecting many others.

Also the natural selection on viruses would result in them evolving into less deadly forms because those would be the ones that get more wide spread.

Other factors like long incubation and infectiousness are also often inversely correlated the incubation period is the time when the virus replicates while remaining mostly asymptomatic which often means for airborne viruses it’s also a period when the host isn’t particularly infectious.