This study looks at how effective and safe a medicine called crovalimab is for people with a rare disease called atypical Hemolytic Uremic Syndrome (aHUS). This condition causes blood clots in small blood vessels, which can lead to kidney damage.

To join the study, participants must weigh at least 40 kg (about 88 pounds) and have had specific vaccinations. If they are already taking other medicines, their doses need to be stable for at least 28 days. Women who can have babies need to use birth control and have a negative pregnancy test before starting the study. Some people can't join if they have other kidney diseases or infections like HIV or Hepatitis.

• Study Length: The study does not specify the duration, but participants must meet all requirements before starting.
• Participation: Participants need to have recent vaccinations and stable doses of any current medications.
• Risks: Participants are screened for other health conditions to reduce risks.