Sequela

Etymology

From Latin "sequela" (that which follows), from "sequi" (to follow) — the same root as "sequence" and "consequence." Medicine adopted it for a pathological condition that follows in the wake of an earlier one. The plural, "sequelae," is common in clinical writing.

noun · /sih-KWEL-uh/
A lasting condition that is the consequence of a previous disease or injury.
What it names
A useful precise term for the aftermath of an illness — the lingering nerve pain after shingles, the fatigue that outlasts an infection — naming the downstream effect as distinct from the original acute event.
Example
The exhaustion and brain fog were sequelae of the virus, persisting long after the fever itself had broken.
Related idea
Contrast with a comorbidity (already here), a separate condition co-occurring with another; a sequela is specifically caused by the prior illness, following from it rather than merely accompanying it.