The US Food and Drug Administration (FDA) today approved the varicella immune globulin preparation Varizig (Cangene) for reducing the severity of chickenpox infections in high-risk individuals when given within 4 days after exposure.
Varicella-zoster virus (VZV) causes chickenpox in children and shingles in adults. Varizig is the only FDA-approved immune globulin for VZV after exposure available in the United States. It was designated as an orphan drug by the FDA and received a priority review.
Most people in the United States have immunity to VZV from vaccination or from having had chickenpox during childhood, the FDA said in a press release. However, people without immunity to VZV who are exposed to the virus may experience severe infections that are sometimes fatal.
People most at risk include children or adults with weakened immune systems, pregnant women, and infants exposed during pregnancy or after birth. Occasionally, healthy people without immunity to VZV may contract severe infections. Antiviral treatments are not always effective and cannot be used in some cases.
"This approval fills an unmet need by providing a treatment to lower the risk of severe, potentially fatal varicella infections in vulnerable patients," Karen Midthun, MD, director of the FDA's Center for Biologics Evaluation and Research, said in the press release.
Varizig is an antibody preparation manufactured from plasma of healthy donors with high anti-VZV antibody levels. Varizig is administered in 2 or more injections, depending on the weight of the recipient, within 96 hours after exposure. Varizig is approved for immunocompromised children and adults, newborns, pregnant women, premature infants, children younger than 1 year, and adults with no immunity to VZV.
Varicella-zoster immune globulin (VZIG) has been shown to lower the risk for severe infections if given soon enough after exposure. An earlier FDA-licensed VZIG was removed from the US market by the manufacturer in 2006, and Varizig has only been available under an investigational expanded-access protocol during the licensing process.
The most common adverse effects with Varizig are pain at the injection site and headache.
Varizig is manufactured by Cangene Corporation in Winnipeg, Canada.