Coloured magnetic resonance imaging (MRI) scan of the brain of a patient with active covid-19 and multisystem inflammatory syndrome in adults (MIS-A). Lesions (red) in the splenium of the corpus callosum (centre left) and in the cerebral white matter are highlighted. MIS-A is a rare but severe complication of covid-19 infection that usually presents 4 to 6 weeks after infection. It causes inflammation in multiple organ systems including the brain, heart, lungs and gastrointestinal system, so symptoms can be wide ranging. MIS-A can be fatal especially if not diagnosed and treated early enough.