“Seth material” search engine (Jane Roberts)

Specific inoculations are given under various conditions. They are bound to affect the biological system. The people who take such inoculations within your own culture, now, usually do so because they do not want the disease specified, and they believe that the inoculation will prevent it. It is impossible to tell ahead of time how many of those individuals would come down with the disease otherwise, yet diseases do come and go whether or not inoculations are given. The mechanisms operate in such a fashion that by now overall belief has come to such a point that the same results would almost be effected if an inoculation of no particular value were given instead. The mind is as effective against viruses as anything else—and in such hypothetical cases immune reactions would be set up biologically, through the mind’s beliefs.

Diseases have been wiped out through the use of inoculations. In past cultures, diseases have been wiped out through the intercession of good spirits. The specific nature of inoculations, however, means that more and more become necessary in that system, for the fear of each newly discovered disease becomes paramount—and no time is given, in your terms, now, for the body to respond naturally to those natural conditions, and therefore build up a natural immunity, biologically speaking.