Inclusion Criteria:  Male and female participants ≥ 18 years of age with a diagnosis of PNH confirmed by high-sensitivity flow cytometry with clone size ≥ 10% Mean hemoglobin level <10 g/dL LDH > 1.5 x Upper Limit of Normal (ULN) Vaccination against Neisseria meningitidis infection is required prior to the start of study treatment If not received previously, vaccination against Streptococcus pneumoniae and Haemophilus influenzae infections should be given  Exclusion Criteria:  Prior treatment with a complement inhibitor, including anti-C5 antibody Known or suspected hereditary complement deficiency History of hematopoietic stem cell transplantation Patients with laboratory evidence of bone marrow failure (reticulocytes <100x109/L; platelets <30x109/L; neutrophils <0.5x109/L). Active systemic bacterial, viral (incl. COVID-19)or fungal infection within 14 days prior to study drug administration. History of recurrent invasive infections caused by encapsulated organisms, e.g. meningococcus or pneumococcus. Major concurrent comorbidities including but not limited to severe kidney disease (e.g., dialysis), advanced cardiac disease (e.g., NYHA class IV heart failure), severe pulmonary disease (e.g., severe pulmonary hypertension (WHO class IV)), or hepatic disease (e.g., active hepatitis) that in the opinion of the investigator precludes participant's participation in the study.  Other protocol defined inclusion/exclusion criteria may apply.