Hmm, interesting. I don't object to the new definition- the old one explicitly calling out cowpox feels outdated as our medical technology has marched on. You

Hmm, interesting. I don't object to the new definition- the old one explicitly calling out cowpox feels outdated as our medical technology has marched on. You make a very good point though, depending on what definition of "vaccine" one used prior to 2020 the mRNA vaccines might not fall under it. And changing the meaning of the word doesn't magically change the properties of the things it refers to.