, 2 Fine PE Herd immunity: history, theory and practice. 2 Fine PE Herd immunity: history, theory and practice. Herd immunity is a real phenomenon that occurs whether the immunity generated is naturally acquired or vaccine-induced. 4 BBC NewsnightCoronavirus: can herd immunity protect the population?. I strongly dissociate myself from any link with this meaning and clarify that I was referring to herd immunity purely in the scientific sense.