Thank you @amandajro for your reply. Exactly, a host is needed for the survival of the virus. Can you please explain how a vaccinated individual cannot be a host when the vaccine does not prevent covid infection? Those are contradicting reports. Very confusing. Am I wrong? Since it has been said the vaccine may only reduce the severity of the illness but not prevent a vaccinated individual from spreading the infection. In a vaccinated individual the virus will meet more resistance for its survival than in a non vaccinated person. That would be a more likely reason for the covid virus to mutate. Logic would make sense in a non vaccinated individual the virus meets less resistance for its survival and therefore less likely for the virus to mutate. In other words, the virus has no reason to develop a harsher strain to keep existing. Please correct me if my thinking is wrong.