Keep in mind the mRNA is not the end product in either case. It is just a set of instructions.
In the case of the vaccine, there are two further steps afterwards: An induced protein spike, and THEN the desired outcome of body-produced antibodies (and, eventually, T cells).
In the case of 2-73, there are also two further steps: The production of mRNA and THEN the desired outcome of more Sigma 1 receptors.
In each case the body is stimulated into taking the final desired step itself.