The Immunes are a cult of people unaffected by the Red Flu found by the Ramsey brothers. Their speaker is Kevin MacDowell, an immune from Ireland. They believe those who survived are meant to inherit the earth and saw the cure as an act of sacrilege. They believe themselves to be chosen and saw the USS Nathan James as a threat against everything they stand for. They mostly operate in the Southern Parrish and their moving base of operations is the HMS Achilles, a British Royal Navy Submarine. After learning Dr. Niels Sørenson was behind the Red Flu and was test subject zero, they welcomed him with open arms, believing him as their 'Messiah'. Later on in the show, the Achilles was sunk during a battle with the Nathan James and MacDowell and any of his followers were arrested or killed. Curtis, who was the remaining Immune alive and free, killed Dr. Rachel Scott outside her hotel, but later in the show, was in prison for her murder.