Immunity
Immunity was the natural ability of an organism's immune system to fight off infections and diseases.
The children under the age of four of five of a group of Human colonists, later known as Novans, were able to build up an immunity against the radioactive debris of an asteroid. (ENT: "Terra Nova")
On the M-class planet Valakis, the Menk had a natural immunity against a plague the Valakians suffered from. (ENT: "Dear Doctor")
In 2152, Doctor Phlox used a medical scanner to confirm that the Takret anatomy was immune to radiolytic isotopes. (ENT: "The Catwalk")
T'Pol's Vulcan k-cells were immune and neutralized the mutagenic virus created by the Loque'eque. (ENT: "Extinction")
When Captain James T. Kirk was up to stop Charlie Evans, Doctor McCoy reminded him that he did not have any special immunity anymore. (TOS: "Charlie X")
Captain Ronald Tracey found that the atmosphere of the planet Omega IV provided him immunity to the Omega IV virus. (TOS: "The Omega Glory")
When Doctor McCoy treated Spock's choriocytosis with injections of a synthesized drug, the Vulcan body started to build up an immunity after two days. (TAS: "The Pirates of Orion")
Vulcans were among the species known to have a natural immunity against the Dramia II plague. (TAS: "Albatross")
The physicians at the Darwin Genetic Research Station on Gagarin IV genetically-engineered Human children were designed to resist disease. (TNG: "Unnatural Selection")
When Doctor Beverly Crusher removed the proximity detector from Ishara Yar, she noted that her metabolism, immunity, all other vital signs were excellent. (TNG: "Legacy")
While Doctor Julian Bashir assisted in the destruction of the Harvesters, he noted that he had "never seen a nano-biogenic weapon so resistant to broad spectrum radiation." (DS9: "Armageddon Game")
Most Humans had a natural immunity against Urodelan flu, except Reginald Barclay. (TNG: "Genesis")
The Vidiians searched for centuries for a species immune to the phage until chief surgeon Sulan found the Klingon B'Elanna Torres in 2371. (VOY: "Faces")
The toxin the Nechani monks acquired before entering the biogenic field produced the natural immunity. (VOY: "Sacred Ground")