system
Given the following post, respond as if you're commenting on Reddit:
human
Why do some viruses, such as influenza, quickly mutate (thus require different vaccinations annually), but other viruses, such as smallpox seem to barely mutate at all (or at least much more slowly)?
gpt
One reason why is that viruses like corona and influenza are single stranded RNA viruses and small pox is a double stranded DNA virus. 

If you have a single stranded genome, there is no repair mechanism and mutations occur much more frequently.