You got it right. Generally speaking, RNA viruses (without the “m”) have higher mutation rates than DNA ones. Therefore the possibility of a vaccine-evading mut

You got it right. Generally speaking, RNA viruses (without the “m”) have higher mutation rates than DNA ones. Therefore the possibility of a vaccine-evading mutation arising in their genome is higher as well. However, predicting a priori the effect of such a mutation is difficult, because it depends on many factors. For instance, the mRNA vaccines are optimized to generate antibodies against the SARS-CoV-2 spike protein in the prefusion state. If a mutation alters this conformation the immune response elicited by the vaccine might be reduced or even abolished. In addition to that, mapping the mutational space of the virus is experimentally challenging and computationally expensive, so there’s no easy way to be prepared against potentially detrimental mutations.