Evolution occurs at all time scales and for most organisms. It is a very complex process, part of which is natural selection. Covid mutates and replicates very quickly, and it is evolving towards highly contagious but not killing the host (which also ensures the virus will be around longer). Because the Covid RNA mutates rapidly, the vaccines are not as effective as for pestilences with very slow stable DNA mutations, such as smallpox and polio.

Ironic, but some people don't trust the covid vaccine because it came out too quickly, even though it was the result of decades of combined research on genetics, diseases, and treatments, They really should have a Noble prize for this. Covid and vaccines require a lot more study, but that will take longer than it took to develop the vaccine. Research and scientific publications require a lot of study and documentation.