Prospective participants must have primary wAIHA as well as other protocol-defined criteria. After participants have been determined to be eligible for the study, they will be randomized to 2:1, with stratification factor of corticosteroid dose and hemoglobin (Hgb \<9 g/dL or ≥ 9 g/dL). Once a participant has completed the week 24 assessments in the double-blind period, the participant will have the opportunity to receive parsaclisib in the open-label treatment which will last up to another 24 weeks. Participants may then continue to receive parsaclisib in a long-term extension period.