Can certian symptoms of a disease be produced without the germ present in the body?

"Instead, this theory claims that the radiation from 5G is what’s actually causing COVID-19 symptoms."
https://www.forbes.com/sites/brucelee/2020/04/09/5g-networks-and-covid-19-coronavirus-here-are-the-latest-conspiracy-theories/?sh=4c0ace8e6d41

"Royal Rife went so far as to claim that any disease could be produced by the chemical constituents of a virus enacting upon an unbalanced cell metabolism in the body. In his experiments with animals, he said he was able to produce all the symptoms of a disease without inoculating and virus of bacteria into the animal"
http://www.drrife.com/

Exposure to a 50 Hz electromagnetic field induces activation of the Epstein-Barr virus genome in latently infected human lymphoid cells
https://pubmed.ncbi.nlm.nih.gov/9276003/