Given that, no, I don't want to be part of the testing of this new medical technology. Personally I'd want to see at least 10 years or more of long-term study of the side effects (or hopefully lack thereof). I'd also like to see this used in several different cases. Since (again hopefully) we're not likely to see widespread vaccinations again anytime soon...and given my age and my family's demonstrated life expectancy... I'm fairly certain I'll never take anything to do with mRNA technology. Good luck with that world, not my problem.
The use of adenoviruses for gene therapy is more than 20 years old. That's what the J&J does, and it winds up producing the mRNA that the other two vaccines injject directly. The existing gene therapy use is mainly to enhance the immune system to fight cancer and genetic diseases.
The mRNA technology has been studied since Hungarian born biochemist researcher, Katalin Karikó in 1990, learned that mRNA told cells which proteins to make. What is new is the breakthrough technology that is used to deliver the bluprint RNA message to the translation machinery of the target cell’s ribosomes. That medical miracle is the lipid nanoparticle.