Thank you for kindly answer @Frederic Lepretre

I think that the majority of mutants are spontaneous , since RNA molecule is unstable , in addition , the RNA polymerase lack the fidelity and proof reading activity

Thanks for the answer Zahra Al-Khafaji

hi

human had thousand of years to adapt itself to selective pressure of the environment, as other species. for viruses as CORONA, the limitation is helped by the replication rate and speed. since viruses are prone to mutation due to their genome replication speed and higher instability, not surprising that errors in RNA editing will offer the possibility of new members from the same strain.

stay safe

fred