Eculizumab in Pediatric and Adult Participants With Atypical Hemolytic Uremic Syndrome (aHUS) in China

Inclusion Criteria: 1. Any age weighing ≥ 5 kg 2. Complement treatment naïve with evidence of TMA. 3. History of aHUS prior to kidney transplant,or persistent evidence of TMA at least 4 days after modifying the immunosuppressive regimen. 4. Among participants with onset of TMA postpartum, persistent evidence of TMA for \> 3 days after the day of childbirth 5. All participants must be vaccinated against N meningitidis if not already vaccinated within the time period of active coverage specified by the vaccine manufacturer. 6. Participants \< 18 years of age must have been vaccinated against Haemophilus influenzae type b (Hib) and Streptococcus pneumoniae according to local vaccination schedule guidelines. 7. In participants receiving treatment with medications known to cause TMA, persistent evidence of TMA at least 4 days after modifying the excluded medication Exclusion Criteria: 1. Known familial or acquired ADAMTS13deficiency (activity \< 5%). 2. ST-HUS as demonstrated by local guidelines. 3. Positive direct Coombs test which is indicative of a clinically significant immune-mediated hemolysis not due to aHUS. 4. HIV infection, and /or unresolved meningococcal disease 5. Ongoing sepsis, and / or presence or suspicion of active and untreated systemic infection 6. Organ transplantation history, and/or Bone marrow transplant/hematopoietic stem cell transplant within 6 months prior to the start of Screening. 7. Among participants with a kidney transplant, acute kidney dysfunction within 4 weeks of transplant consistent with the diagnosis of acute antibody-mediated rejection. 8. Among participants without a kidney transplant, history of kidney disease other than aHUS 9. Identified drug exposure-related HUS, and / or HUS related to vitamin B12 deficiency and / or known genetic defects of cobalamin C metabolism. 10. History of malignancy within 5 years of Screening. 11. Known systemic sclerosis (scleroderma), systemic lupus erythematosus, or antiphospholipid antibody positivity or syndrome. 12. Chronic dialysis. 13. Prior use of complement inhibitors. 14. Use of tranexamic acid within 7 days prior to the start of Screening. 15. Other immunosuppressive therapies. 16. Receiving chronic intravenous immunoglobulin (IVIg) within 8 weeks prior to the start of Screening. 17. Received vasopressors or inotropes within 7 days prior to Screening. 18. Previously or currently treated with a complement inhibitor. 19. Has participated in another interventional treatment study or used any experimental therapy. 20. Hypersensitivity to any excipient in eculizumab. 21. Pregnant or breastfeeding.