Brunner HI, Tzaribachev N, Cornejo GV, et al. - This research attempted to evaluate protective antibody responses to diphtheria and tetanus vaccination given before study enrolment in patients with polyarticular-course juvenile idiopathic arthritis (pJIA). Researchers performed a substudy of a 24-month, single-arm, open-label, multicenter, Phase III trial of subcutaneous abatacept including a total of 219 children with active pJIA. This study examined a total of 29 individuals: 19 (65.5%), 1 (3.4%) and 9 (31.0%) individuals had > 12, 6–12 and 2–< 6 months of abatacept exposure, respectively. The results of this study displayed that individuals aged 2–5 years with pJIA who received 2–24 months of weekly subcutaneous abatacept, with or without concomitant methotrexate and/or low-dose corticosteroids, maintained effective diphtheria and tetanus vaccination protection without new safety signals.