# Safety and Pharmacokinetics of Nirsevimab in Japanese Infants: Primary Analysis of the Open-Label JUBILUS Trial **Authors:** Masaaki Mori, Susannah Leach, Maria Learoyd, Divya Vijapur, Sam Sadow, Deidre Wilkins, Yoshifusa Abe, Kazushige Ikeda, Hirokazu Kanegane, Zempei Kano, Hiroyuki Moriuchi, Jun Muneuchi, Ryuta Nishikomori, Kaoru Okazaki, Therese Takas, Ayako Sakaguchi, Tonya Villafana PMC · DOI: 10.1093/jpids/piag008 · 2026-03-24 ## TL;DR A study found that nirsevimab is safe and effective in Japanese infants at risk for severe respiratory infections. ## Contribution The study confirms nirsevimab's safety and pharmacokinetic profile in Japanese infants, supporting its use in this population. ## Key findings - Nirsevimab was well-tolerated with no safety concerns observed in Japanese infants. - Serum concentrations of nirsevimab were consistent with previously established efficacy levels. ## Abstract In Japanese infants aged ≤12 months at risk for severe respiratory syncytial virus-associated lower respiratory tract infections who received two doses of nirsevimab 5–6 months apart, no safety concerns or anti-drug antibodies occurred. Nirsevimab serum concentrations were consistent with those previously demonstrated to be efficacious in healthy preterm and term infants. ## Full-text entities - **Diseases:** sepsis (MESH:D018805), ADA (MESH:D016736), Down syndrome (MESH:D004314), congenital heart disease (MESH:D006330), respiratory tract disease (MESH:D012140), infantile spasms (MESH:D013036), deaths (MESH:D003643), preterm birth (MESH:D047928), infections (MESH:D007239), LRTIs (MESH:D012141), heart valve prolapse (MESH:D016127), bronchitis (MESH:D001991), RSV disease (MESH:D018357), SAEs (MESH:D064420) - **Chemicals:** palivizumab (MESH:D000069455), ADA (-), Nirsevimab (MESH:C000709769) - **Species:** Respiratory syncytial virus (no rank) [taxon 12814], Homo sapiens (human, species) [taxon 9606] ## Figures 1 figure with captions in the complete paper: https://tomesphere.com/paper/PMC13025070/full.md --- Source: https://tomesphere.com/paper/PMC13025070