It's easy to suppress older, non-narrative conforming information these days by simply not including such materials in official digitization efforts. The largest digitization of old books effort in the world is literally run by google, a company heavily invested in vaccines; so you could well expect never to find these books included in their efforts.
The books were digitized independently by British man John Wantling, a victim of mercury amalgam poisoning, using the Manchester Library
http://whale.to/a/wantling_h.html
It's easy to suppress older, non-narrative conforming information these days by simply not including such materials in official digitization efforts. The largest digitization of old books effort in the world is literally run by google, a company heavily invested in vaccines; so you could well expect never to find these books included in their efforts.