Not at all. Self-realization (also known as enlightenment, Nirvana, Moksha, knowledge of (what/who we call) God, and other synonyms) completely removes fear of death as well as all suffering. It also almost completely mitigates the anxiety stemming from uncertainty of (future) unknown (i.e. fear of the way of dying).

In other words, irrational fear of death and dying is not our end game. It's enough to put the metacognitive faculties that cause it into proper perspective. And the only way to go about it is self-realization because that's the only absolute point in the world of relative (beside death, that is).

So yeah, indefinitely, but only until one knows themselves ;)