What effect can mutations have on virus

Mutation takes place in viruses as they occur in a cellular organism, the presence of a large number of mutants in the virus genome give virus population ability to adapt quickly to selective pressures

Some viruses like influenza and HIV virus mutate so rapidly from one host to another host cell that it becomes very difficult for the immune cell to prepare antibodies or for the scientist to prepare a vaccine against the viruses.

meteorologists would compare a new weather map with one 24 h old to see how fast a front is moving.