General Information

VariZIG (Varicella Zoster Immune Globulin [Human]) is a solvent/detergent-treated sterile lyophilized preparation of purified human immune globulin G (IgG) containing antibodies to varicella zoster virus (anti-VZV). It provides passive immunization for non-immune individuals exposed to VZV, reducing the severity of varicella infections.

VariZIG is specifically indicated for post-exposure prophylaxis of varicella in high-risk individuals. High-risk groups include: immunocompromised children and adults, newborns of mothers with varicella shortly before or after delivery, premature infants, neonates and infants less than one year of age, adults without evidence of immunity and pregnant women.

Mechanism of Action

VariZIG, Varicella Zoster Immune Globulin (Human) is a solvent/detergent-treated sterile lyophilized preparation of purified human immune globulin G (IgG) containing antibodies to varicella zoster virus (anti-VZV). VZV is the causative agent of chickenpox. VariZIG is prepared from plasma donated by healthy, screened donors with high titers of antibodies to VZV, which is purified by an anion-exchange column chromatography manufacturing method. This donor selection process includes donors with high anti-VZV titers due to recent natural infection by VZV, or due to recurrent zoster infection (shingles).

Side Effects

Adverse events associated with the use of VariZIG may include, but are not limited to, the following:

• pain at the injection site
• headache

Dosing/Administration

VariZIG is supplied as a solution for intramuscular administration. VariZIG should be administered as soon as possible following varicella zoster virus (VZV) exposure, ideally within 96 hours for greatest effectiveness. Dosing of VariZIG is based on body weight. See label for recommendations. The minimum dose is 62.5 International Units (IU) for small infants under two kilograms body weight; the maximum dose of 625 IU should be administered for all patients greater than 40 kilograms in weight.

Clinical Trial Results

The FDA approval of VariZIG was based in part on a randomized, open-label, multicenter, active-controlled clinical trial in 60 pregnant women without immunity to VZV, as confirmed by a latex agglutination test. The women were stratified on the basis of time from first exposure to varicella as follows: one to four days post-exposure and five to 14 days post-exposure. The women were randomized into one of three study arms: a single intravenous dose of 125 IU/10 kg body weight to a maximum dose of 625 IU; a single intramuscular dose of 125 IU/10 kg body weight to a maximum dose of 625 IU or a single intramuscular dose of 125 IU/10 kg body weight to a maximum dose of 625 IU of VZIG (licensed comparator product). The subjects were followed for 42 days. Incidence of clinical varicella was similar across all treatment groups with an overall incidence of 33 percent; however, in the subset of 28 subjects with more than 24 hours exposure to varicella, the incidence of clinical varicella in the combined treatment groups was 64 percent. Mean weighted constitutional illness scores (CIS) (6) were similar across all groups and none of the subjects had serious complications of varicella.