COVID-19 vaccine-associated myositis

A 53-year-old healthy man received the first dose of the ChAdOx1 nCoV-19 vaccine (COVISHIELD) into his left deltoid muscle. He experienced pain in the left upper arm, followed by the right upper arm and bilateral calf muscles (left more than right). The pain gradually increased, restricting his daily activities. On the 11th day of vaccination, he had difficulty walking and moving his left arm. He also reported generalized muscle weakness, more pronounced in the proximal upper and lower limbs than the distal ones. His medical history was unremarkable with no evidence of COVID-19 infection in the past.

Serologic testing yielded mildly increased serum creatine kinase (187 U/L, reference range 40–171 U/L) and alanine transaminase (50 U/L, reference range 10–40 U/L) concentrations. Serum bilirubin, aspartate aminotransferase (AST), gamma glutamyl transpeptidase (GGT), alkaline phosphatase (ALP), and C-reactive protein levels were normal. Urine analysis excluded myoglobinuria. 

On MRI, edema was observed in the left deltoid muscle with a thin layer of subfascial fluid adjacent to the muscle belly (see Figure). Deltoid muscle architecture was preserved. Subtle edema was also noted in the medial head of the left gastrocnemius muscle, with the edema fluid tracking along the intermuscular plane between the gastrocnemius and soleus. No collection or abscess was seen. MRI of the right arm and leg was normal. Based on the findings, a diagnosis of COVID-19 vaccine-associated myositis was made. 

On the first follow-up after 1 week (18th day of vaccination), the pain and tenderness had reduced considerably. However, the difficulty in walking persisted. It improved with rest after 5 weeks.

Autoimmunity associated with vaccines may be related to specific HLA phenotypes, the development of autoantibodies, or even evolve into a rheumatological disorder. Few of the other reported cases of vaccine-induced autoimmunity include optical neuromyelitis, transverse myelitis, autoimmune encephalitis, sensory neuropathy, and polyarthritis autoimmune rheumatoid arthritis. One case was followed by fatal breakthrough infection

The antibodies against SARS-CoV-2 spike glycoproteins have been suggested as a possible cause for acute autoimmune responses. Other proposed mechanisms include cytokine-mediated autoinflammation, CD8 T-cell overactivation, formation of antigen–antibody complexes, and structural deformity of myocytes caused by intake of viral antigen.


Bose P, Goenka U, Moitra S, Majumdar S, Goenka MK, Sen SG. COVID-19 vaccine-associated myositis - a case report. Clin Case Rep. 2022 Sep 12;10(9):e6314. doi: 10.1002/ccr3.6314. PMID: 36110335; PMCID: PMC9465691.


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