• Vaccines

Varizig Generic Name & Formulations

General Description

Varicella zoster immune globulin (human) 125 IU; per vial; soln for IM inj; contains <180mg of total protein (mostly human IgG), <40mcg/mL of IgA; preservative- and mercury-free.

Pharmacological Class

Immune globulin.

How Supplied

Single-use vial—1


Store Varizig at 2 to 8° C (36 to 46° F). Do not freeze. 

Generic Availability


Mechanism of Action

Varizig provides passive immunization for non-immune individuals exposed to varicella zoster virus (VZV), reducing the severity of varicella infections.

Varizig Indications


Postexposure prophylaxis of varicella in high risk individuals (include immunocompromised children and adults, newborns of mothers with varicella shortly before or after delivery, premature infants, neonates and infants <1 year old, adults without evidence of immunity, pregnant women). To reduce severity of varicella.

Varizig Dosage and Administration

Adults and Children

See full labeling. Administer one single-dose by IM inj ideally within 96 hours of exposure. Based on patient size: divide dose and give in ≥2 inj sites; max 3mL per inj site. Inject into deltoid muscle or anterolateral aspects of the upper thigh. Avoid gluteal region; if needed, only use upper, outer quadrant. ≤2kg: 62.5 IU; 2.1–10kg: 125 IU; 10.1–20kg: 250 IU; 20.1–30kg: 375 IU; 30.1–40kg: 500 IU; ≥40.1kg: 625 IU. Consider 2nd full dose for high risk patients with additional exposure >3 weeks after initial dose.

Varizig Contraindications


IgA-deficiency with IgA antibodies and history of hypersensitivity. Previous severe reaction to human immune globulin.

Varizig Boxed Warnings

Not Applicable

Varizig Warnings/Precautions


Risk for thrombotic events: in patients with history of atherosclerosis, multiple cardiovascular risk factors, advanced age, impaired cardiac output, prolonged immobilization periods, and/or known/suspected hyperviscosity. Risk for hyperviscosity (including those with cryoglobulins, fasting chylomicronemia/markedly high triglycerides, or monoclonal gammopathies); monitor baseline blood viscosity. Severe thrombocytopenia. Coagulation disorders. Have epinephrine inj (1:1000) available. Contains human albumin; potential risk for infection transmission (eg, viruses, Creutzfeldt-Jakob disease). Elderly. Pregnancy. Nursing mothers.


Transmissible Infectious Agents

  • Varizig is made from human plasma; it may carry a risk of transmitting infectious agents, eg, viruses, the variant Creutzfeldt-Jakob disease (vCJD) agent and, theoretically, the Creutzfeldt-Jakob disease (CJD) agent.
  • Plasma donors are screened for the presence of certain infectious agents and the manufacturing process for Varizig includes measures to inactivate and remove certain viruses. Despite these measures, products derived from human plasma can still potentially transmit diseases.
  • No cases of transmission of viral diseases, vCJD or CJD have been associated with the use of Varizig.

Pregnancy Considerations

Animal reproduction studies have not been conducted with Varizig. It also is not known whether Varizig can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity.

Administer Varizig to a pregnant woman only if clearly needed.

Nursing Mother Considerations

It is not known whether Varizig is excreted in human milk.

Use caution when Varizig is administered to a nursing mother.

Pediatric Considerations

The safety and effectiveness of Varizig have been evaluated for post-exposure prophylaxis in the Varizig expanded access clinical trial in 374 pediatric patients, including immunocompromised pediatric patients:

  • 94 preterm newborns and infants,
  • 53 term newborns,
  • 45 infants and toddlers,
  • 176 children and,
  • 43 adolescents.

Geriatric Considerations

Clinical studies of Varizig administered intramuscularly for post-exposure prophylaxis did not include sufficient numbers of elderly participants (aged ≥65 years) to determine whether they respond differently from younger participants.

In patients aged ≥65 years who are determined to be at increased risk of thrombotic events, exercise caution with Varizig. Do not exceed recommended doses and administer Varizig intramuscularly only.

Varizig Pharmacokinetics


Half-life: 26.2 ± 4.6 days.

Varizig Interactions


May affect response to live virus vaccines; may defer until 3 months after Varizig administration.

Varizig Adverse Reactions

Adverse Reactions

Inj site pain, headache, chills, fatigue, rash, nausea; hypersensitivity reactions (discontinue if occurs).

Varizig Clinical Trials

Clinical Trials

Pregnant Women Exposed to Varicella Zoster Virus

A randomized, open-label, multicenter, active controlled clinical trial was conducted in 60 pregnant women without immunity to VZV (as confirmed by a latex agglutination test).

  • Patients were stratified on the basis of time from first exposure to varicella as follows:
    • 1 to 4 days post-exposure and,
    • 5 to 14 days post-exposure.
  • The women were randomly assigned into 1 of 3 study arms as follows:
    • a single IV dose of 125 IU/10 kg to a max dose of 625 IU of Varizig,
    • a single IM dose of 125 IU/10 kg to a max dose of 625 IU of Varizig or,
    • a single IM dose of 125 IU/10 kg to a max dose of 625 IU of VZIG (licensed comparator product).
  • Patients were followed for 42 days.
  • Incidence of clinical varicella was similar across all treatment groups with an overall incidence of 33%; however, in the subset of 28 patients with more than 24 hours exposure to varicella, the incidence of clinical varicella in the combined treatment groups was 64%.

High Risk Patients Exposed to Varicella Zoster Virus

An open-label, Expanded Access Protocol (EAP) conducted in the US was designed to provide Varizig to high risk individuals who were exposed to varicella zoster virus (VZV). The study was not designed to evaluate efficacy, however, the objective was to further assess and confirm the safety/efficacy of Varizig IM injection in the prevention or reduction of severity of complications from varicella infections in the indicated high risk populations. Initially, enrollment was limited to allow treatment with Varizig only within 96 hours of exposure, but later amended to a treatment window of 10 days post-exposure.

  • The incidence of clinical varicella (chickenpox lesions), was compared to predefined historical reference rates.
  • The incidence of severe varicella complications, including pneumonia, encephalitis, severe varicella with pox counts >100 pox, mortality and all complications was also evaluated.
  • The overall incidence of clinical varicella was evaluated in an interim analysis, where 10% (31/311) of high risk individuals exposed to VZV and treated with Varizig for all combined populations, for whom complete or partial efficacy data was available.
  • Clinical varicella was observed in 8.4% (13/154) of immunocompromised pediatric and adult patients, in 6.8 % (5/74) of pregnant women, in 14.8% (12/81) of infants and one healthy adult.
  • Clinical varicella was more common after prolonged VZV exposure.
  • The final report confirmed the efficacy results in the interim analysis.
  • Updated final results of clinical varicella was observed in 4.5% (12/269) of immunocompromised pediatric and adult patients, in 7.3% (10/137) of pregnant women, in 11.4% (12/105) of infants (including newborns, preterm infants, infants aged <1yr). 

Moreover, a comparison of the incidence of varicella based on the treatment window revealed that treatment between 5 and 10 days post-exposure was no different from treatment within 96 hours.

Varizig Note

Not Applicable

Varizig Patient Counseling

Patient Counseling

Inform patients of the following:

  • Varizig is intended to reduce the severity of chickenpox infections. Contact your healthcare provider if you develop the signs/symptoms of varicella.
  • Varizig is prepared from human plasma and therefore, may contain infectious agents such as viruses that can cause disease.
  • There is also the possibility that unknown infectious agents may be present in such products.
  • Persons known to have severe, potentially life-threatening reactions to human immune globulin products should not receive Varizig or any other immune globulin products unless the risk has been justified.
  • Persons who are deficient in IgA may have the potential for developing anti-IgA antibodies and have severe potentially life threatening allergic reactions.
  • Immune globulin administration may interfere with the response to live virus vaccines (eg, measles, mumps, rubella and varicella), and patients should notify their immunizing physician of recent therapy with Varizig.