Interleukin-1/6 Blockade for the Treatment of Severe Steroid-Refractory BNT162b2 Vaccine-Induced Adult-Onset Still’s Disease

INTRODUCTION: Several immune-mediated side effects have been reported with COVID-19 vaccines, including myocarditis. CASE DESCRIPTION: A 27-year-old woman with a past medical history of mild COVID-19, developed adult-onset Still’s disease (AOSD) with salmon-pink flagellate erythema, polyarthritis, a sore throat, myocarditis and haemophagocytic lymphohistiocytosis after receiving two doses of the BNT162b2 vaccine (Pfizer(®), BioNTech(®)). Despite the initial efficacy of high-dose pulses of methylprednisolone, inflammatory markers rose as soon as de-escalation of corticosteroids was attempted, warranting initiation of biologics targeting the interleukin (IL)-1/6 axis, which allowed sustained remission of the disease despite withdrawal of corticosteroids. DISCUSSION: To our knowledge, this is the first case of AOSD with both haemophagocytic lymphohistiocytosis and cardiac magnetic resonance imaging-proven myocarditis triggered by COVID-19 vaccination, successfully treated with steroids and biologics targeting the IL-1/IL-6 axis. The pathophysiological process by which COVID-19 vaccination can lead to AOSD is still unknown, although it has been reported that the spike protein may act as a pathogen-associated molecular pattern and thus induce an overproduction of pro-inflammatory cytokines of the innate immune system (e.g., IL-1, IL-6 or IL-18). CONCLUSION: Targeting the IL-1/6 axis is effective for the treatment of severe steroid-refractory BNT162b2 vaccine-induced adult-onset Still’s disease. At a population level, the favourable benefit/risk ratio of COVID-19 vaccination remains indisputable. LEARNING POINTS: Adult-onset Still’s disease can be triggered by the BNT162b2 COVID-19 vaccine. Biologics targeting the interleukin-1/6 axis should be considered early in the course of vaccine-induced adult-onset Still’s disease, especially when steroids do not effectively curb the disease.