I don't think all is viral mimicry.

Some viruses stay latent in the body... Epstein Barr and Herpes Simplex and Herpes Zoster, and many others. Our immune systems keep them in check, but they can erupt anytime. Drugs that suppress the immune system may activate them. Chemo drugs may activate them, aging or stress may activate them.
Alot depends on your genetic ability to cope with them.

The shingles virus (Herpes Zoster) lives in the dorsal root ganglia of the spinal cord and waits for opportune times to activate. Most of the research has been done on it.

There are even studies showing virus incorporation into the epigenetic (or so called junk) DNA in humans and being passed down thru the chromosomes in many generations to offspring!

It can get pretty complicated! Mimicry is only one form of attack.

Glenn will come on here I hope to explain molecular mimicry in more detail.

Vaccines however, may in some people with genetic inclinations, create a situation where antibodies are formed that react to the adjuvants in the vaccines, which then attack the recipient. Squalene, is one adjuvant that has been shown in animals to cause autoimmune attack.