Illusion is false information.It could be a total fabrication and non-existent IT for all we know.
Delusion is an action based upon illusion.
Ification is the process of being.
Fortunately your Creator has endowed you with 5 senses. If you think something exists but nothing from that thing hits any of your senses then the only environment that thing exists in is your own mind. Things in your mind cannot be vanquished by vaccination.