What Mutations of SARS-CoV-2 are Causing Concern?.
The mutation rate of ssRNA viruses is observed to be much higher than organisms that possess ssDNA, and many times more than those with dsDNA. Not all mutations necessarily increase virulence, and in the majority of cases may in fact be deleterious or inconsequential.
Therefore, organisms must find an equilibrium between a high mutation rate that allows them to adapt to changing environmental conditions, and a low one that lessens the incidence of catastrophic mutations. Small DNA viruses may encode for their own DNA repair, and some RNA viruses also share the ability to check for and repair replication errors.