Eculizumab will be administered at a dose of 900 mg every 2 weeks, as per the dosing schedule described above.
Crovalimab will be administered at a dose of 1000 mg IV (for participants with body weight between 40 and 100kg) or 1500 mg IV (for participants with body weight >=100kg) on Week 1 Day 1. On Week 1 Day 2 and on Weeks 2, 3 and 4, it will be administered at a dose of 340 mg SC. For Week 5 and Q4W thereafter, it will be administered at a dose of 680 mg SC (for participants with body weight between 40 and 100kg) or 1020 mg SC (for participants with body weight >=100kg). Dosing schedule will be as described above.