Varicella zoster immune globulin (VariZIG, Saol Therapeutics) is a human blood product prepared from plasma obtained from healthy, volunteer blood donors identified by routine screening to have high antibody titers to varicella-zoster virus. The first varicella zoster immune globulin, VZIG, became available in 1978. In a study of immunocompromised children who were administered VZIG within 96 hours of exposure, approximately one in five exposed children developed clinical varicella, and one in 20 developed subclinical disease compared with 65%—85% attack rates among historical controls. In 2006, VZIG was discontinued and a new product, VariZIG, became available.
Ask the Experts: Varicella (Chickenpox): Varicella Zoster Immune Globulin
Varicella zoster immune globulin, VariZIG (Saol Therapeutics), is recommended for patients without evidence of immunity to varicella who are at high risk for severe varicella and complications, who have been exposed to varicella or herpes zoster, and for whom varicella vaccine is contraindicated. Patient groups recommended by CDC to receive VariZIG include the following:
- Immunocompromised patients without evidence of immunity
- Newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (i.e., 5 days before to 2 days after)
- Hospitalized preterm infants born at 28 weeks or more of gestation whose mothers do not have evidence of immunity to varicella
- Hospitalized preterm infants born at less than 28 weeks of gestation or who weigh 1,000 grams or less at birth, regardless of their mothers’ evidence of immunity to varicella
- Pregnant people without evidence of immunity
CDC recommends administration of VariZIG as soon as possible after exposure to varicella-zoster virus, ideally within 96 hours, but not beyond 10 days after exposure. The most recent recommendations for the use of VariZIG were published in 2013 and are available at www.cdc.gov/mmwr/pdf/wk/mm6228.pdf on pages 574—576.
VariZIG is supplied in 125-IU vials and should be administered intramuscularly as directed by the manufacturer. The recommended dose is 125 IU/10 kg of body weight, up to a maximum of 625 IU (five vials). The minimum dose is 62.5 IU (0.5 vial) for patients weighing 2.0 kg or less and 125 IU (one vial) for patients weighing 2.1–10.0 kg. VariZIG is available from Saol Therapeutics. For ordering information see varizig.com/liquid-product_info.html.
There is no evidence that healthy full-term infants born to women in whom varicella occurs more than 48 hours after delivery are at increased risk for serious complications such as pneumonia or death. Varicella zoster immune globulin, VariZIG, can be given up to 10 days after exposure but is only recommended for newborn infants whose mothers have signs and symptoms of varicella around the time of delivery (5 days before to 2 days after), hospitalized premature infants born at 28 or more weeks of gestation whose mothers do not have evidence of immunity to varicella, or hospitalized premature infants born at less than 28 weeks of gestation or who weigh 1,000 grams or less at birth regardless of their mothers’ evidence of immunity to varicella. Assuming this is an infant at home, VariZIG would not be recommended. Varicella, if it develops, would be managed as for any child.