It is large groups of unvaccinated people in which SARS-CoV-2 continues to spread, allowing it to mutate, that is responsible for the variants we are seeing.
We have all of the answers to your questions about the COVID-19 vaccines.
Viruses with variants aren’t anything new. The COVID-19 variants are a concern because some of them are more contagious, more deadly, and may lead to vaccine failures.
An attenuated vaccine is one that has been weakened, so that it can’t make you sick, but will still trigger the creation of antibodies and an immune reaction.