You won't see any evidence. None can exist for something that does not exist!
The victims of that claim are not insane but desperately gullible. They may too, have had little or no basic science and engineering education even at school. They may have little or no appreciation of hazard and risk - which are not synonyms. They might be more afraid of injections than of diseases.
It's not even logical; and belongs in the same rubbish-bin as microchips via 5G signals, perpetual motion, shielded "anti-radiation" wallets for portable telephones, alchemy, von Daniken's alien fantasies and the Cottingley Fairies photographs*.
At least we can excuse the Mediaeval - Renaissance alchemists by the dubious "benefit" of their era's common genuine ignorance mixed with mysticism; but even many of their contemporaries doubted their claims.
Someone somewhere wilfully started this ridiculous "microchip" idea, obviously; but whether we will ever know who and why, is another matter. Although he or she cannot claim ignorance as an excuse, not in the 21C.
.
*The "Fairies": A 19C practical joke perpetrated by two girls in the town of Cottingley. It spiralled rapidly out of their control after supposedly intelligent grown-ups, including professional mystery-peddler Arthur Conan-Doyle, failed to think fully, properly and logically about the photographs. The same failure exhibited now by the believers in microchip-injections and similar fantasies.
