Primary Immune Deficiencies (PIDs) can be defined as defects in the immune system.
No, that can’t be enough.
PIDs are defined as inherent defects in the immune system?
Nope. Still not good enough.
PIDs are defined as the susceptibility to rare pathogens?
We’ve known about PIDs atleast since the 1950s. We shed a tear at the John Travolta movie “The boy in the plastic bubble” (partly because of the movie but mostly because it had John Travolta). Indeed, Severe Combined Immunodeficiency (SCID) as described in the movie is the most well known of the PIDs. But is that all? Are PIDs simply the abcence of a functioning immune system?