Possibly the joke is about one-upmanship.
Convicts comparing their crimes.
Convict 1: I’m in for burglary.
Convict 2: I’m doing 10 years for murder.
In Matts version, convict 1 has come back from an area with low covid, convict 2 from a high area with a variant. Convict 2 is bragging his crime is more edgy.