I'm not a virologist. But from what I heard on the radio months ago, the virus gets a chance to mutate when its in immunocompromised people. So the people that tend to get really sick and get RONA will have it stay in their body much longer than 14 days. In that environment, the compromised immune system can't kill it so it has more chances to mutate. The vaccines are 90%+ effective in preventing infection, and 100% effective in preventing serious infection.
www.sciencemag.org
Noroviruses are the leading cause of acute gastroenteritis outbreaks worldwide. The majority of norovirus outbreaks are caused by genogroup II.4 (GII.4). Novel GII.4 strains emerge every 2 to 4 years and replace older variants as the dominant norovirus. ...
www.ncbi.nlm.nih.gov
The case history of a U.K. man in his 70s shows how selective “pressures” bring about viral mutations
www.scientificamerican.com
So basically, widespread vaccination EARLY is by far the best thing we can do to help combat further mutations.