Son had hpv shot last saturday wednesday night told me armpit lymph node now swollen painful cbc normal dr said reaction to shot is this possible ?

Vaccine ?'s: Any vaccine contains elements called antigens, which evoke an antibody response to the vaccine to protect against future infections with whatever the vaccine is designed to prevent. This can cause a temporary lymph node reaction which may be painful.

Very much so: This is a sign of a good immunologic reaction to the vaccine - so it's working well, and no worries