No. They are actually incredibly safe, much safer than the vaccines from last century. The big scandal from 1955, where an improperly killed polio vaccine gave polio to 40,000 kids, leaving 51 paralyzed and 5 dead, is literally impossible with mRNA vaccines.

As a doctor, I consider mRNA vaccines to be one of the most exciting developments in vaccine history. It has the potential to make vaccines something that a developer can encode, much like a programmer writing a computer program. The possible applications of this are insane.