I'm neither a doctor nor working in the medical field, but using vaccine for antiserum would bother me.
Fortunately in german they used "Impfstoff" what literally means "the stuff you put into the patient with a syringe". It can be a cure or a vaccine, but in any case when you hear the word you think of a syringe. So what threw me off was that the sims were drinking it. Granted, we used to get oral vaccinations in school (the vaccine on sugar cubes and little me hated the sugar more than the vaccine), so it wasn't unthinkable. Still, it's not the first action that comes to mind.
