Varicella Immunoglobulin Dosing Guidelines

Introduction to Varicella Zoster Immune Globulin

The recommended dose of varicella zoster immune globulin (VariZIG) is 125 IU per 10 kg of body weight, administered intramuscularly, up to a maximum of 625 IU (five vials), as recommended by the Centers for Disease Control and Prevention (CDC) 1

For patients weighing ≤2.0 kg, the minimum dose is 62.5 IU (0.5 vial) 1
For patients weighing 2.1–10.0 kg, the minimum dose is 125 IU (one vial) 1
For patients >10 kg, the dose is 125 IU per 10 kg body weight, capped at 625 IU total 1

VariZIG should be administered intramuscularly as directed by the manufacturer, with the product injected directly into the deltoid or gluteal muscle using an appropriate needle length for the patient's age and size, as per the manufacturer's instructions 1
Administer VariZIG as soon as possible after varicella exposure, ideally within 96 hours, but it can be given up to 10 days post-exposure, according to the CDC 1, 3

Immunocompromised patients without evidence of immunity should receive VariZIG, as recommended by the CDC 1, 3
Newborn infants whose mothers developed varicella 5 days before to 2 days after delivery should receive VariZIG, as recommended by the CDC 1
Hospitalized premature infants ≥28 weeks gestation whose mothers lack immunity to varicella should receive VariZIG, as recommended by the CDC 3
Hospitalized premature infants <28 weeks gestation or weighing ≤1,000 g at birth, regardless of maternal immunity status, should receive VariZIG, as recommended by the CDC 3
Pregnant women without evidence of immunity should receive VariZIG, as recommended by the CDC 3

Individuals with verified positive varicella IgG levels (except bone marrow transplant recipients) are considered immune and do not require prophylaxis, as stated by the American Academy of Pediatrics 4, 5
Patients receiving monthly high-dose IGIV (>400 mg/kg) are likely protected if the last dose was within 3 weeks of exposure, according to the American Academy of Pediatrics 4
For high-risk patients with additional varicella exposures ≥3 weeks after initial VariZIG administration, another dose should be considered, as recommended by the CDC 1

Observe patients closely for 28 days after exposure and institute antiviral therapy immediately if signs or symptoms of varicella develop, as recommended by the CDC 1
Delay varicella vaccination for ≥5 months after VariZIG administration to avoid interference with vaccine response, as recommended by the CDC 1

Pain at injection site (2%) and headache (2%) are the most frequent side effects, as reported by the CDC 1
History of anaphylactic or severe systemic reactions to human immune globulins is an absolute contraindication, as stated by the FDA 1, 4
IgA-deficient patients with antibodies against IgA and history of hypersensitivity should not receive VariZIG, as stated by the FDA 5
Pregnancy and lactation are not contraindications, according to the manufacturer's instructions 2