[danieltillett]

The problem with polio back mutating is limited to one of the three strain in the live vaccine and is due to the mutations not being deletion mutations. The live polio vaccine was developed before people knew this and for regulatory reasons the problem has never been fixed.

This problem is easy to avoid these days.

[ztjio]

I have no reason to believe you're wrong, I just wanted to point out that we (as a whole community of scientists etc.) can observe an entire range and lifecycle of this approach and that we're aware of the risks based not only on theory but on practice.

Personally I see your proposal as a relatively worthy endeavor to consider.