Study to Evaluate the Efficacy and Safety of PANZYGA in Pediatric Patients With Chronic Immune Thrombocytopenia (ITP)

Inclusion Criteria: 1. Females and males aged from ≥1 year to \<18 years old 2. Confirmed diagnosis of Chronic Immune Thrombocytopenia (ITP) according to American Society of Hematology (ASH) 2019 guidelines 3. Platelets count \<30x10\^9/L at the Baseline Visit 4. Voluntarily given written informed consent (provided by patient's parent or legal guardian) and assent (provided by patient \[if age-appropriate per IRB (Institutional Review Board) requirements\]) 5. Sexually active females who have been using at least 1 acceptable form of birth control for a minimum of 30 days (or a minimum of 3 months for hormonal contraceptives) prior to the Screening visit and must agree to use at least 1 acceptable method of contraception throughout the study and for 30 days after the last dose of PANZYGA. Acceptable methods of birth control for this study include: intrauterine device (IUD), hormonal contraception, male or female condom, spermicide gel, diaphragm, sponge, or cervical cap. For non-sexually active females who have begun menstruating, abstinence is considered an acceptable method of birth control. 6. Parent or legal guardian must agree and be willing to assist the participant attend study visits, and to follow all protocol requirements and instructions of the study doctor Exclusion Criteria: 1. Thrombocytopenia secondary to other diseases (such as Acquired Immunodeficiency Syndrome \[AIDS\] or systemic lupus erythematosus \[SLE\]), drug-related thrombocytopenia, or congenital thrombocytopenia 2. Administration of intravenous immunoglobulin (IGIV) or anti-D immunoglobulin within 3 weeks (+/- 3 days) before enrollment 3. Administration of thrombopoietin receptor agonists when the dose has NOT been stable within 3 weeks before enrollment and a dosage change is planned before Day 32 4. Administration of oral immunosuppressants when the dose has NOT been stable during the preceding 2 months (2 weeks for long-term corticosteroid therapy) and a dosage change is planned before Day 32 (Note: topical agents and inhaled corticosteroid therapy use is permitted) 5. Administration of long-term anti-prolific agents or attenuated androgen therapy when the dose has NOT been stable during the preceding 2 months and a dosage change is planned before Day 32 6. Nonresponsive to previous treatment with IGIV or anti-D immunoglobulin 7. Evidence of an active major bleeding episode at Screening 8. Splenectomy in the previous 3 months or planned splenectomy throughout the study period 9. Evans syndrome (experiencing active disease with 2 out of 3 of the following: autoimmune thrombocytopenia, autoimmune hemolytic anemia, and/or autoimmune neutropenia) 10. Known or suspected human immunodeficiency virus (HIV), hepatitis B virus (HBV), and/or hepatitis C virus (HCV) infections 11. Emergency surgery in the previous 4 weeks 12. Severe liver and/or kidney disease (alanine aminotransferase \[ALT\] \>3x upper limit of normal (ULN), aspartate aminotransferase \[AST\] \>3x upper limit of normal (ULN), and/or creatinine \>120 µmol/L) 13. History of severe hypersensitivity to blood or plasma derived products, or any component of the PANZYGA 14. Known immunoglobulin A (IgA) deficiency and antibodies against IgA 15. History of, or suspected alcohol or drug abuse in the previous year 16. Females who are pregnant or nursing 17. Unable or unwilling to comply with the study protocol 18. Receipt of any other investigational medicinal product within 3 months before study entry 19. Risk factors\* for thromboembolic events in whom the risks outweigh the potential benefit of PANZYGA treatment. 20. Any other condition(s), that in the Investigator's opinion, make it undesirable for the patient to participate in the study or may interfere with protocol compliance. * Risk factors include, but are not limited to: obesity, advanced age, hypertension, diabetes, a history of atherosclerosis/vascular disease or thrombotic events, hyperlipidemia, multiple cardiovascular risk factors, acquired or inherited thrombophilic disorders, prolonged periods of immobilization, severe hypovolemia, central venous catheterization, active malignancy and/or known or suspected hyperviscosity.