Why do you think they changed the definition? Did you even read them? Covid vax are first that don't target the virus. That's why only last 3 months
Trigger immune response GENERALLY
So it's telling your body to go on defense with or without any threat present.
No tiny amount of the virus to your system to teach it to fight THAT virus
Body fighting NOTHING
They didn't actually change the definition. At most some websites corrected their wrong definition. What you show as the old definition was only a definition of one type of vaccine.
The mRNA vaccine type is more effective at teaching your body how to build immunity. It is also safer than old traditional vaccines. It's also easier to produce and make other vaccines
