A rare presentation of rapidly progressing myopathy in an adolescent.

We present a case of severe juvenile dermatomyositis (JDM) with limited response to steroids in an adolescent who developed symptoms within hours after receiving Pfizer BNT162b2 COVID-19 vaccine. The patient presented with severe weakness of proximal muscles, dyspnoea and tachycardia. His muscle enzymes were raised, and he was diagnosed with severe JDM following magnetic resonance imaging (MRI) and muscle biopsy. His management was challenging, requiring multidisciplinary input, and difficult decisions with regards to the appropriate immunomodulatory treatments. The patient had to undergo escalating immunosuppressive treatments before he began to recover clinically and biochemically. To our knowledge this is the first case in an adolescent, although a few cases of similar presentations following COVID-19 vaccination have been reported in adults. Elucidating the potential relationship of the vaccine with this severe myopathy in an adolescent is important for global vaccination policies but avoiding the conflation of association with causation is also crucial in the context of the pandemic.