Vaccination in Juvenile Idiopathic Inflammatory Myopathies: Current Evidence-Based Recommendations

Abstract

Juvenile Idiopathic Inflammatory Myopathies (JIIMs), a rare group of chronic autoimmune conditions in children below 18 years include Juvenile Dermatomyositis (JDM), juvenile polymyositis, immune-mediated necrotizing myopathy (IMNM) and the overlap myositis syndromes. While diagnostic classifications have delineated their subtypes based on myositis specific/associated antibodies and imaging advancements, treatment strategies continue to evolve from the broad blunt-force immunosuppression of Corticosteroids  and Methotrexate [conventional disease-modifying antirheumatic drugs (DMARDs)] as first-line agents, to the precision strikes of biological DMARDs [including Rituximab, Abatacept, Interleukin Inhibitors (ILIs) and Tumour Necrosis Factor Inhibitors (TNFIs)] and targeted synthetic DMARDs (including Janus Kinase Inhibitors (JKIs) and Brepocitinib) against refractory JIIMs. This narrative review, collated until August 2026, elucidates recent key diagnostic and therapeutic advances and enumerates relevant immunization strategies recommended by leading international bodies. Despite documented temporal associations, current evidence is insufficient to establish a causal relationship between any specific vaccine and the onset, flare, or relapse of JIIMs. Low-dose immunosuppressive therapy singly [Corticosteroid (<20 mg/day or 2 mg/Kg/day of Prednisone or equivalent, short or long term or alternating days), Methotrexate (<0.4 mg/kg/week or <20 mg/week), Azathioprine (<3 mg/kg/day), or 6-Mercaptopurine (<1.5 mg/kg/day)] is not a contraindication to live vaccine administration. Provided disease activity allows, for seasonal killed influenza vaccine, Rituximab and Methotrexate are better deferred to 2 weeks post vaccination; COVID-19 vaccination scheduled 4 weeks before next planned Rituximab or 1 week before intravenous Abatacept, while Methotrexate and subcutaneous Abatacept are better discontinued for 1-2 weeks post-vaccination. For killed Pneumococcal, Human Papillomavirus (HPV) and Herpes Zoster (HZ) vaccines (age>18 years), vaccination can be scheduled when the next Rituximab cycle is due, then Rituximab (except for HZ) and Methotrexate (except for HPV) deferred for 2 weeks post-vaccination. For non-live vaccination, routine post-vaccination interruption of Abatacept, TNFIs, ILIs or JKIs is currently not recommended, unlike Methotrexate or Rituximab. Live vaccines (MMR and varicella) are best administered either 2 weeks before or 3-11 months after Intravenous Immunoglobulin therapy. Live vaccines should normally be administered 4 weeks before therapy begins or atleast 3 months after therapy ends; and avoided during JKIs or biologic therapy, and 6-12 months after B-lymphocyte depleting Rituximab. Live vaccines are contraindicated during Calcineurin Inhibitors (Tacrolimus, Cyclosporin), Mycophenolate Mofetil, and Sirolimus (each regardless of dose) therapy. Non-live and live vaccines are to be administered at least 3 and 12 months after stopping Chimeric antigen receptor (CAR) T-cell regimen, respectively.