Eligible participants will be randomized to receive intravenous (IV) infusion of eculizumab or placebo at a 2:1 ratio. All participants will be on concomitant IV immunoglobulin G (Ig) therapy as per standard of care.
This is a Phase 3, prospective, multicenter, placebo controlled, double blind, randomized study to investigate the efficacy and safety of eculizumab in participants with severe GBS, defined using the Hughes Functional Grade (FG) scale as progressively deteriorating FG3 or FG4/FG5 within 2 weeks from onset of weakness due to GBS.~This study will be conducted only at sites in Japan.