More generally, vaccines are just a mechanism for acquiring immunity. Immunity doesn't mean "you don't feel sick," it means "your immune systems responds better and faster to the real thing."
I do not need to need to be educated about how vaccines work, I know that there is a secondary effect of vaccines that primes your immune system and makes the disease easier to fight. But it's a secondary effect, otherwise we would call more things "vaccines", as we know that for example "exercise helps with immune response".
The fact that people confuse the two is a legitimate public education problem. But it doesn't change what they actually are, or how medical professionals use the word.
> But it's a secondary effect, otherwise we would call more things "vaccines", as we know that for example "exercise helps with immune response".
It is the effect. I think everybody understands the difference between taking care of yourself and receiving a medical preparation that stimulates your immune system against a specific disease.
The CDC changed the definition of vaccine on Sept 2, 2021 and removed the reference to immunity.
[1] https://web.archive.org/web/20210901163633/https://www.cdc.g...
[2] https://web.archive.org/web/20210902194040/https://www.cdc.g...
And just to preempt your question, every news source reachable via Google says the change has nothing to do with COVID or the effectiveness of the COVID vaccine.
> every news source reachable via Google says the change has nothing to do with COVID or the effectiveness of the COVID vaccine.
Either way, it doesn't matter: the website in question is a public information page, not a medical reference. The CDC updated it because it was incorrect, and the timing of their update makes perfect sense given the public's confusion (and predation around that confusion).