Two flares of Still's disease after two doses of the ChAdOx1 vaccine.

We report the case of an 18-year-old male with Still's disease for the last 3 years, in remission, who developed two flares of his disease after receiving two doses of the ChAdOX1 nCoV-19 vaccine. While the first flare was mild requiring steroid initiation and resolved rapidly, the second flare after the second dose was much severe, requiring pulse steroid and tocilizumab. We also review three reported cases of flares of Still's disease after COVID-19 vaccination. The temporal association of the flares with both vaccine doses strengthens the association between the vaccine administration and the flare. The proposed mechanism may be due to activation of the innate immune system by the vaccine adjuvants. This review serves to inform the medical community regarding a possible role of the vaccine in producing a systemic inflammatory response. Early detection and treatment can help reduce morbidity in these cases.