According to this link, the Dominant Delta Variant may mutate itself into destruction.
The Delta variant in Japan was highly transmissible and keeping other variants out.
But as the mutations piled up, we believe it eventually became a faulty virus and it was unable to make copies of itself.
I was told that evolution was about survival of the fittest, and that in the case of virus strains, a more contagious strain would likely increase in frequency relative to a less contagious one. So how can a mutation of the strain Delta which can't replicate or replicate less, increase in frequency relative to the original Delta strain?
Can a less fit strain of a virus impose over a fitter one?