- Diagnosis of a PID disorder as defined by World Health Organization criteria (IUIS Scientific Committee, Primary immunodeficiency diseases. Report of an IUIS Scientific Committee. Clin Exp Immunol. 1999) for which the subject has been receiving a regular regimen of IV immunoglobulin infusions every 21 ± 3 days or 28 ± 3 days or a regular SC immunoglobulin treatment at 1 to 2 week intervals over a period of at least 3 months pre-study at a dose of 300-800 mg/kg BW/4 weeks