Adult multisystem inflammatory syndrome in a patient who recovered from COVID-19 postvaccination

Multisystem inflammatory syndrome in children has become a recognised syndrome, whereas a parallel syndrome in adults, multisystem inflammatory syndrome in adults (MIS-A), has not been well defined. Most cases occur several weeks following confirmed or suspected SARS-CoV-2 infection, but none have been reported in association with SARS-CoV-2 vaccines. Here we describe the case of a 22-year-old man, who received the inactivated SARS-CoV-2 vaccine 6 weeks following a mild COVID-19 infection. He presented after his second dose of the vaccine with a clinical picture of a multisystem inflammatory syndrome-like illness. Additionally, there was laboratory evidence of acute inflammation. The patient's condition markedly improved after initiation of steroids. Whether the vaccine augmented an already-primed immunity from the infection and contributed to the occurrence of MIS-A is difficult to prove. Understanding the pathogenesis of this condition will shed light on this question and entail major implications on treatment and prevention.