Well, we know they have ghosts in Iceland, or can at least pretty safetly say so because
and we can also assume they have ghosts in Finland based on
And they're probably also available in Norway based on Sigrun's reaction when Reynir mentioned ghosts. Look at her being all serious
and then straight to the necessary information:
so ghost are not necessarily born from use of the serum. On the other hand we can guess that the use of the serum might be what have caused the ghosts to remain for so long, based on a certain comment from Onni:
so... uh... I don't really know where I'm going with this buuuut... maybe the serum is connected to the
state of the ghosts more than the fact there is ghosts. So far it has seemed that the Serum Ghosts are more angry and linger on longer than the Normal Ghosts, and why shouldn't they be angry? They were treated with something that was supposed to be a cure, but instead killed them. Brain dead, so maybe they even had to sit there and watch as their bodies was kept alive, knowing fully well they'd never be able to return to them. I dunno, I'm not sure how brain death works.