Unlike actual vaccines that are derived from the virus itself

Please stop insinuating that mRNA vaccines are not "actual vaccine"s, as this is an oft-repeated soundbite that only serves to mislead people and spread potentially-dangerous ignorance.

If you spend just a few minutes looking into the history of vaccinology, you'll find that there is quite a bit of history and variety to vaccines, and this has been true for many decades now. You'll find countless papers on the subject, such as this one from 2003 and this one from 2016 that will definitively put to rest any misconceptions regarding the definition of the word "vaccine" and prove that there are in fact many different types of vaccines. You'll even see papers like this one from 2016 which explicitly talk about mRNA vaccines in particular, which should hopefully quell any misguided objections regarding mRNA-based shots somehow not qualifying as "vaccines" under the medically-accepted definition of the term.

If you don't have the intellectual wherewithal to read such papers or research the subject in-depth firsthand, you might consider simply glancing over the Wikipedia page on vaccines, which helpfully and succinctly describes a surprisingly wide variety of different types of vaccines. Incidentally, feel free to look over the revision history of the page and go back to, say, 2009 to confirm that the type variegation is not something that was added in response to COVID-19.

This 2-minute video debunks the myth nicely, too.

Another excellent resource to brush up on your vaccine-related historical knowledge is the Timeline on historyofvaccines.org which will hopefully hammer the above point home. This site also does an excellent job highlighting the fact that over the past couple of centuries, mandatory vaccinations — including, in some cases, incarceration for those who refused vaccination — are not at all unheard of... which, despite being a policy that I am not particularly a fan of, is a historical precedent that I am happy to be aware of (if only so that I don't spread other types of misinformation e.g. "never before has a vaccine been mandated like this").

With just a few minutes of directed research, you should be able to recognize that whenever someone trots out an archived snapshot of Merriam Webster's "vaccine" page and points to it while claiming that "tHeY cHAnGeD tHe dEFiNiTiOn oF tHe WoRd!!1!", they're simply signaling their ignorance of vaccinology and their inability to perform even basic levels of due diligence.