prions perhaps?

Even with prions, there evidence that the body (and probably more so with some people than others) has some level of ability to resist, slow, or sometimes prevent a prion infection.

See these:

- The influence of PRNP polymorphisms on human prion disease susceptibility: an update [1]

- A naturally occurring variant of the human prion protein completely prevents prion disease | Nature [2]

[1] https://pubmed.ncbi.nlm.nih.gov/26022925/

[2] https://www.nature.com/articles/nature14510?utm_source=chatg...