Interesting read:
Summary:
New mRNA vaccine technology has been plagued with problems in the past. The current RNA based SARSCoV-2 vaccines were approved in the US using an emergency order without extensive long term safety testing, steps were skipped in approvals, going directly to human trials without animal testing trials.

Community concerns expressed in the article:
Risk of pathogenic prion formation, known to cause ALS, front temporal lobar degeneration, Alzheimer’s disease and other neurological degenerative diseases.

Risks also include possibility of neurodegeneration such as Jakob-Creutzfeldt disease (in cows its called Mad Cow disease, sheep = scrapie)

Article reference:
https://scivisionpub.com/pdfs/covid19-rna-based-vaccines-and-the-risk-of-prion-disease-1503.pdf