COVID variants

Remember the early days of Covid when experts were excitedly talking about herd immunity (HI) and how things would get back to normal when this was reached? How long has it been since the term was used? The answer is five days.
Are COVID vaccines responsible for creating the multiple variants that keep hitting the world? I get this question all the time in the comments section following ACSH articles about vaccines.
Now we all know that Darwin uncovered the idea of evolution, the survival of the fittest.