Most mutations in SARS-COV-2 are not random but caused by the host intracellular antiviral mechanisms ("host editing"). Because of the host editing, almost half of the nucleotide mutations are C > U transitions. This study observes that none of the 12 most dangerous mutations in the SARS-COV-2 spike of the major pre-Omicron variants included a C > U transition. This observation and the existing body of knowledge support the proposition: coronavirus RNA mutations, caused by the host editing, tend to be less dangerous than mutations from other causes. The main practical conclusion is that mutations introduced externally (such as by Molnupiravir) are more likely to cause dangerous variants. When evaluating mutagen's potential co create dangerous variants of coronavirus, the frequency of mutations caused by it should be compared to frequency of mutations NOT caused by host-editing. Fig. 1. The most dangerous mutations in spike, RBD. T19R is not shown.