The presence of SARS-CoV-2 spike protein might have been due to vaccination rather than viral infection, because no SARS-CoV-2 nucleocapsid protein was detected. The spike protein in the central nervous system might have been related to the acute ischemic change, and that in the pituitary and adrenal glands may have been associated with right heart failure, possibly through dysfunction of the renin-angiotensin-aldosterone system.

We investigated mRNA vaccine effects in a chronic inflammation mouse model implanted with an LPS pump, focusing on toxicity and immunogenicity. Under chronic inflammation, mRNA vaccines exacerbated cardiac damage and myocarditis, inducing mild heart inflammation with heightened pro-inflammatory cytokine production and inflammatory cell infiltration in the heart. Concurrently, significant muscle damage occurred, with disturbances in mitochondrial fusion and fission factors signaling impaired muscle repair. However, chronic inflammation did