Vaccinee regularly gets skin problem (4)
I believe the answer is:
acne
'skin problem' is the definition.
(I've seen this in another clue)
'vaccinee regularly' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
The alternating letters of 'vaccinee' are 'ACNE'.
'gets' is the link.
(Other definitions for acne that I've seen before include "(Inflammation causing) spots" , "Spotty complaint" , "Pimply skin condition of adolescence" , "Spotty coverage" , "Skin rash" .)