A human plasma-derived immunoglobulin G (IgG) formulation containing high levels of antibodies against varicella zoster virus (VZV), a double-stranded DNA virus that causes chickenpox and herpes zoster (shingles), with potential immunomodulating and antiviral activities. VZV IgG (VZIG) is isolated from donors expressing high amounts of VZV antibodies. Upon intramuscular (IM) administration, the anti-VZV antibodies provide passive immunization against VZV. This may prevent infection by VZV in immunocompromised patients.