Category 2 was a category of the categories of life system instated in light of Miracle Day, which resulted in the human race becoming immortal for several months in 2011. (TV: The Blood Line) Category 2 were those persons with non-fatal but lasting illnesses or injuries. Though Category 2s might be severely injured, they were not brain dead and could function with a degree of independence. Under the emergency Miracle law, all those designated Category 2 were to be taken to the overflow camps alongside the Category 1s, those with fatal illnesses or injuries. In the camps, Category 2 patients were identified with a blue peg.
In reality, the line between the categories was dubious. A Category 1 could become Category 2, should they recover; Rex Matheson should have been killed when he was impaled by a rebar, but healed over time. Likewise, a Category 2 could slide into Category 1 without proper treatment. Individuals such as Geraint Cooper (who lapsed into a deep coma after suffering a stroke) were lumped into Category 1 with the truly brain-dead. (TV: The Categories of Life)
British citizens designated as Category 2 were expelled from Europe, with a cruise ship dropping them off in Cardiff. (TV: The Middle Men)