What about the smallpox vaccine? This is a peculiar case. You see, if you vaccinate someone who is an anthroposophist and has been anthroposophically trained, it does no harm. (alternative: You see, if you vaccinate someone who is an anthroposophist, or bring someone up anthroposophically, it does no harm.) It only harms those who grow up with predominantly materialistic thoughts. In this case, vaccination becomes a kind of Ahrimanic force; the person is no longer able to lift himself or herself out of certain materialistic feelings. And this is actually what is so dangerous about the smallpox vaccination, that human beings are literally permeated (durchkleidet) by a phantom (entity). The person has a phantom which prevents him/her from getting rid of soul entities out of the physical organism, as is possible in normal consciousness. He or she becomes constitutionally materialistic, and can no longer raise himself up to the spiritual. That is the danger of vaccination. Of course, it will always be about statistics, which will guide the issue. The question is precisely in these issues, whether statistics should have such a high value (importance) attached to them.
With smallpox vaccination, it is very strongly about something psychological. It cannot be ruled out that the belief that vaccination helps plays an incalculably large role. If humans were to replace this belief with something else, if people were brought up (educated) in a natural way, so that they could be influenced (impressed) by something else other than by vaccinating them, for example, if they were brought closer to the spiritual, it would be entirely possible to counter the unconscious intrusion (thought) – ‘we have smallpox epidemic!’ – what would work equally well is principally to consider how we would have to strengthen human beings against such influences – in full consciousness of this: ‘Here is a spirit entity, albeit an unwanted (spurious) spirit, against which I must maintain my own being!’ (… gegen das ich mich aufrechthalten muss!)
English translation by Christine Howard of an excerpt on small pox vaccination from: Rudolf Steiner, Physiologisch-Therapeutisches auf Grundlage der Geisteswissenschaft (Rudolf Steiner Verlag, 1989), 287-88