This is a common misconception. Viruses mutate, sure, but most do not mutate very quickly or very much. This includes coronaviruses. Influenza, on the other

This is a common misconception. Viruses mutate, sure, but most do not mutate very quickly or very much. This includes coronaviruses. Influenza, on the other hand, mutates at a prodigious rate in meaningful ways. The reason we don't have vaccines against any coronaviruses is because there aren't very many that infect humans and all of them other than SC2 are so mild it isn't worth spending the effort to eradicate them.