Adult-Onset Still's Disease After an mRNA COVID-19 Vaccine in an Older Woman

Adult-onset Still's disease (AOSD) is an uncommon autoinflammatory disorder without a clear etiology that primarily affects young adults. New-onset disease at > 80 years of age is uncommon. We present the case of an 82-year-old woman with AOSD which developed after receiving a messenger ribonucleic acid (mRNA) coronavirus disease 2019 (COVID-19) vaccine. COVID-19 vaccines are known to cause overproduction of cytokines, systemic inflammation, and some immune-mediated adverse events, such as rheumatoid arthritis, systemic lupus erythematosus, dermatomyositis, vasculitis, and polymyalgia rheumatica after the vaccination has been reported. A handful of cases of AOSD after the vaccination have also been reported and the median age was 40s. However, AOSD related to COVID-19 vaccination can develop even in older individuals.