Broadly speaking, most viruses have no mechanism to control mutations other than becoming inactive/nonfunctional. Some bacteria are also like this, in that they

Broadly speaking, most viruses have no mechanism to control mutations other than becoming inactive/nonfunctional. Some bacteria are also like this, in that they can tolerate a high mutation rate without going extinct, while other bacteria have rudimentary control mechanisms that slow their mutation rate in favor of higher survivability and specialization.