Many are "inactive" with research to back their safety and efficacy.
mRNA has been around for a long time and well documented and researched:
https://www.frontiersin.org/articles/10.3389/fimmu.2019.00594/full
During the last two decades, mRNA vaccines have been investigated extensively for infectious disease prevention, and for cancer prophylaxis and therapy. Much progress has been made thus far (19, 20)