You have to keep in mind that there are lots of individual mRNA molecules in each vaccine. So an error won't affect all of them, but only a tiny fraction of the

You have to keep in mind that there are lots of individual mRNA molecules in each vaccine. So an error won't affect all of them, but only a tiny fraction of the total vaccine. The error rate overall should be similar or lower than the error rate for any other mRNA and the viral RNA. The mRNA in the vaccine is not produced chemically, but with an enzyme (polymerase) like mRNA in cells.