Adult-Onset Still's Disease Following COVID-19 Infection in a Patient Receiving Nirmatrelvir/Ritonavir: A Case Report.

SARS-CoV-2 (COVID-19) has been associated with numerous complications, including autoimmune and autoinflammatory diseases. The surge of cytokines following COVID-19 infection or vaccination has been proposed to contribute to immune dysregulation, which might subsequently give rise to an autoinflammatory syndrome. Adult-onset Still's disease (AOSD) is one of the rare autoinflammatory diseases characterized by a surge of cytokines. Although an association between COVID-19 vaccines and AOSD has been reported, an association with COVID-19 infection or nirmatrelvir/ritonavir remains very rare. In this case, we present a patient who developed AOSD after COVID-19 infection and subsequent treatment with nirmatrelvir/ritonavir. After the initial response to glucocorticoids, canakinumab was initiated, resulting in positive clinical outcomes.