Live viral measles-mumps-rubella revaccination and varicella vaccination in children and adolescents with juvenile idiopathic arthritis: a systematic review

The purpose of this systematic review is to synthesize the available evidence on the immunogenicity and safety of live viral measles-mumps-rubella (MMR) booster/revaccination and varicella vaccination in children and adolescents with juvenile idiopathic arthritis. PubMed, Scopus, and Web of Science were systematically searched from inception to October 1, 2025, for studies including patients with juvenile idiopathic arthritis who had received live viral MMR or varicella vaccination and reporting immunogenicity, adverse events, vaccine-strain infection, breakthrough infection, or post-vaccination disease activity. Nine studies comprising 743 patients with juvenile idiopathic arthritis were included: five retrospective studies, three prospective cohort studies, and one open-label randomized controlled trial. Seven studies assessed MMR booster or revaccination, whereas two small prospective cohorts assessed varicella vaccination. MMR booster/revaccination was generally immunogenic and clinically safe in the short term, with no consistent increase in disease activity and no serious vaccine-related complications reported. However, 5-year seroprotection after MMR booster was lower among children receiving biologic disease-modifying antirheumatic drugs (DMARDs) at vaccination than among non-bDMARD users for measles (60% vs 86%), mumps (80% vs 94%), and rubella (60% vs 83%). Varicella vaccination induced protective antibodies in 82-83% of patients after two doses, but antibody levels were lower than those in healthy controls; VZV-specific cellular immunity was detectable in 72% in the larger cohort and appeared to persist longer than humoral immunity. No vaccine-strain varicella infection was reported, although mild breakthrough varicella occurred in some vaccinated patients. CONCLUSION: In clinically stable children with juvenile idiopathic arthritis, the available evidence supports the cautious use of MMR booster/revaccination and varicella vaccination under specialist supervision. The main residual concern is not a consistent safety signal but incomplete or less durable protection in selected biologic-treated patients, particularly for measles and rubella 5 years after MMR booster and for varicella in low responders. These findings support individualized vaccine timing and consideration of post-vaccination serology in selected higher-risk children. WHAT IS KNOWN: • Live viral vaccines in children with juvenile idiopathic arthritis are used cautiously because of concerns about attenuated-virus-related adverse events, disease flare, and reduced immunogenicity during immunosuppressive therapy. • The evidence base is stronger for MMR booster/revaccination than for varicella vaccination, because MMR data include one randomized trial and several larger cohorts, whereas varicella data come from two small prospective cohorts. WHAT IS NEW: • MMR booster/revaccination and varicella vaccination appeared generally safe in clinically stable children with juvenile idiopathic arthritis, with no serious vaccine-related complications or vaccine-strain infections reported in the included cohorts. • Five-year seroprotection after MMR booster was lower in biologic-treated children for measles, mumps, and rubella, supporting individualized vaccine timing and selected post-vaccination serologic monitoring.