Great Question.
I'm not here to teach an immunology class. One can pick that up at your local University or College. A good read on basic vaccines is to study up on how the origin in the nation of TURKEY of tiny amounts of Small Pox doses could help develop a stronger immune system for those exposed, and how Mary Pierrepont (aka Lady Mary Wortley Montagu)
brought the idea of inoculation to England
https://en.wikipedia.org/wiki/Lady_Mary_Wortley_Montagu (Same tech as Polio vax/flu vax)
Here are 3 links that may help you learn how mRNA is new and different.
(There are 2 ways Polio vax is administered. Oral gray solution on a sugar cube, or a shot.
The 3rd world gets the cost effective oral, the 1st world currently gets a jab)
University of Pennsylvania Quaker (school started by Ben Franklin) Medical School 2 Research Scientists rushed to do in 66 days, what usually take 10 years to get approved by the FDA:
Dan Weissman & Katalin "Katie" Kariko
1. https://www.youtube.com/watch?v=fdGj6p2qDdk
Ask yourself what is unique about the NEW mRNA technology
that makes the Covid different than the polio or flu vax, enough for
Katalin Kariko to be awarded the NOBEL PRIZE for Medicine along with Dan Weissman ?
What does Peter Thiel, Elon Musk, Robert Malone MD, or Jay Bhattacharyia, MD NIH Director
say about it ?
"People have no idea what a Revolution in Medicine that mRNA technology is."
-Elon Musk
"We ought to hold a ticker tape parade for the scientists that created the mRNA technology"
-Peter Thiel.
The technology for the Covax from Moderna, Pfizer, & Astrozenica used a new methodology to develop an experimental gene therapy juice they to this day insist on calling it a vaccine, even though the method in which they work is very unique.
Related article of interest link: https://www.bbc.com/news/health-68977026
2. https://www.youtube.com/watch?v=KZQOuvW1Euw
Dr. Robert Malone (whom invented the mRNA technology at UC Davis,
that Kariko used to develop the CoVax with help from Weissman at UPENN)
and Retsif Levi of MIT
3. https://www.youtube.com/watch?v=e2e3QAYrzR0&t=114s
Jay Bhattacharya MD, Current NIH Director, 120+ published Medical Research Randomized Studies at Stanford Medical school, and Professor at the Medical School in Palo Alto.
This interview at the Hoover Institute is one that is insightful into the difference of the Covax and the usual vax process for Polio and annual Flu shots.
Is that backup enough? Your welcome.