There is no such thing as herd immunity. It doesn’t exist in real life. Herd immunity basically means that if enough people become immune to an infection, it will have a harder time replicating and eventually will die out. It was a theoretical idea that some epidemiologists in Baltimore proposed back in the 40s when they were studying the way Measles spread. It never got much notice in the scientific community, as it was always assumed that—like everything else in the world—mother nature always got her way. Viruses and bacteria might sputter out eventually, they might mutate, they might keep going, but whatever happened, it had nothing to do with mankind. Trying to eradicate a virus would be like someone suggesting they could stop waves on the beach. They will come and go with the changing tides or storms or the position of the moon but there is nothing in the world you can do to stop, start, move, or shift them. Nature will always win.