A source for what, that people's immune systems weaken as they age?
WRT Herpes Simplex recurrence in particular: "Causes of recurrence may include: decreased immune function, stress, and sunlight exposure." [1]
This isn't unique to Herpes, if you have HPV it's going to be an increasing nuisance with age. A major component of what makes growing old awful is everything your immune system kept in check slowly consumes you.
WRT Herpes Simplex recurrence in particular: "Causes of recurrence may include: decreased immune function, stress, and sunlight exposure." [1]
This isn't unique to Herpes, if you have HPV it's going to be an increasing nuisance with age. A major component of what makes growing old awful is everything your immune system kept in check slowly consumes you.
[1] https://en.wikipedia.org/wiki/Herpes_simplex