Varivax0.5 ml

Established / Approved Use

Varivax is indicated for active immunization for the prevention of varicella (chickenpox) in healthy individuals 12 months of age and older who have no history of the disease and no evidence of immunity.

Guideline-Supported Uses

• Routine childhood immunization: a two-dose series given as part of the standard national/international immunization schedule.
• Catch-up vaccination: susceptible adolescents and adults who have not previously received Varivax or had confirmed varicella.
• Post-exposure prophylaxis: when given within 3-5 days of exposure to a case of varicella, Varivax can prevent or significantly modify (reduce severity of) the disease in susceptible contacts, per current public health guidance.
• Occupational and household-contact vaccination: susceptible healthcare workers, teachers, childcare staff, and household contacts of immunocompromised persons, to reduce transmission risk.

Varivax is not intended for treatment of active varicella or herpes zoster infection.

Each reconstituted 0.5 mL dose of Varicella Virus Vaccine contains a specified minimum potency of live, attenuated varicella-zoster virus (Oka/Merck strain or an equivalent WHO-approved attenuated strain), propagated in human diploid cell culture.

The lyophilized powder also contains stabilizing and processing excipients such as sucrose, gelatin (in some formulations), sodium chloride, and trace residual components (e.g., neomycin) from the manufacturing process. Varicella Virus Vaccine is supplied with a separate diluent (sterile water for injection) for reconstitution immediately before use.

Varivax is a live, attenuated viral vaccine used to actively immunize individuals against varicella (chickenpox), a highly contagious disease caused by the varicella-zoster virus. Varivax contains a weakened form of the virus that stimulates the immune system to produce protective antibodies and cell-mediated immunity without causing the natural disease in most healthy recipients.

Varivax is supplied as a lyophilized (freeze-dried) powder that must be reconstituted with the accompanying diluent and administered by subcutaneous injection.

Varivax belongs to the therapeutic class of Vaccines - Live Attenuated Viral Vaccines, and is classified as an active immunizing agent within the broader category of viral vaccines used for the prevention of vaccine-preventable childhood and adult infectious diseases.

Varicella Virus Vaccine works by introducing a live, attenuated (weakened) strain of varicella-zoster virus that replicates minimally in the recipient without producing significant clinical disease. This limited replication is sufficient to stimulate both humoral (antibody) and cell-mediated immune responses similar to those produced by natural infection.

Following a complete two-dose series, Varicella Virus Vaccine produces seroconversion in the great majority of healthy recipients, and clinical trials and post-marketing surveillance have demonstrated durable protective efficacy against varicella, with a two-dose schedule providing higher efficacy and better protection against breakthrough disease than a single dose.

Protection typically develops within a few weeks of vaccination and, per available long-term follow-up data, is expected to be long-lasting in most recipients, although breakthrough varicella (usually mild) can occasionally occur.

Varivax must be administered by subcutaneous injection only, preferably into the outer aspect of the upper arm (deltoid region) in older children and adults, or the anterolateral thigh in infants. Varivax must never be given intravenously or intramuscularly.

Only the diluent supplied with Varivax should be used for reconstitution (see Reconstitution). The reconstituted vaccine should be injected immediately, and a separate sterile syringe and needle should be used for each individual.

• Salicylates/aspirin: should be avoided for 6 weeks after receiving Varivax because of a theoretical association between salicylate use, varicella (wild-type or vaccine strain), and Reye's syndrome.
• Antiviral agents active against herpesviruses (e.g., acyclovir, valacyclovir, famciclovir): may reduce the effectiveness of Varivax if given shortly before or after vaccination; avoid these agents from 24 hours before to 14 days after Varivax, when feasible.
• Immune globulins and antibody-containing blood products: can interfere with the immune response to Varivax; a specified interval before and after Varivax administration should be observed per current immunization guidelines.
• Immunosuppressive therapy (e.g., high-dose corticosteroids, chemotherapy, biologic immunosuppressants): reduces the immune response to Varivax and increases the risk of disseminated vaccine-strain infection; see Contraindications.
• Other live vaccines: Varivax can generally be given simultaneously with other live vaccines at separate injection sites; if not given on the same day, a minimum interval of about 4 weeks is recommended between Varivax and another live vaccine.

Most reactions to Varivax are mild and self-limited.

• Very common/common: injection-site pain, redness, or swelling; low-grade fever; mild irritability (in young children).
• Common: a mild, localized or generalized varicella-like rash appearing 5-26 days after vaccination.
• Uncommon: headache, malaise, upper respiratory symptoms.
• Rare: more extensive rash, secondary bacterial skin infection, mild transient thrombocytopenia (temporal association reported).
• Very rare/serious: anaphylaxis, encephalitis, pneumonia, and other severe allergic or neurologic reactions have been reported very rarely following Varivax; seek urgent medical attention if these occur.

Pregnancy: Varivax is contraindicated during pregnancy because it contains a live, attenuated virus with a theoretical risk to the fetus. Women should avoid becoming pregnant for at least one month (per current guidance) after each dose of Varivax, and pregnancy should be excluded before vaccination when relevant. If Varivax is inadvertently given during pregnancy, the physician should be informed for appropriate monitoring and counselling.

Lactation: Data suggest the vaccine virus from Varivax is not commonly secreted in breast milk in a manner that causes disease in the infant; however, Varivax should be used in a breastfeeding woman only if clearly needed and after consulting a physician, weighing the potential benefit against any theoretical risk.

• Deferral for acute illness: administration of Varivax should be postponed in individuals with moderate or severe acute illness (with or without fever) until recovery.
• Secondary transmission: as Varivax contains a live virus, recipients who develop a vaccine-associated rash should avoid close contact with susceptible high-risk individuals (pregnant women without immunity, and immunocompromised persons) until the rash resolves, because of a rare risk of secondary transmission.
• Salicylate avoidance: avoid aspirin/salicylate-containing products for 6 weeks after Varivax (see Interactions).
• Two-dose series: a complete two-dose course of Varivax is generally required for optimal, durable protection; a single dose provides only partial protection.
• Breakthrough varicella: Varivax does not eliminate all risk of varicella after vaccination; breakthrough disease can still occur but is typically milder than natural infection in an unvaccinated person.
• Immunocompromised household contacts: use caution when vaccinating close contacts of immunocompromised individuals; discuss with a physician.
• Appropriate medical support: Varivax, like all injectable vaccines, should be given where appropriate medical treatment for rare anaphylactic reactions is available.

There is no established clinical scenario of "overdose" with Varivax in the manner of a pharmacologic drug; however, administration of a higher-than-recommended dose or an extra/unscheduled dose of Varivax is not expected to increase efficacy and could increase the likelihood of local or systemic reactions. If an excessive or accidental repeat dose of Varivax is given, or if a severe reaction is suspected, seek immediate medical attention or contact emergency medical services for evaluation and supportive care.

Store Varivax in a refrigerator (2°C-8°C), protected from light, as per the manufacturer's cold-chain instructions; some presentations may require frozen storage before reconstitution - follow the product-specific label. The diluent may be stored separately at room temperature or refrigerated. Once reconstituted, use Varivax immediately and discard if not used within the time specified on the label (typically within 30 minutes). Keep out of reach of children.

• Immunocompromised individuals: Varivax is generally contraindicated in individuals with significant immunodeficiency (see Contraindications); vaccination of specific low-risk groups (e.g., certain children with leukemia in remission) may be considered only under specialist oncology/immunology supervision.
• Elderly: Varivax is not part of routine elderly immunization for chickenpox prevention (a separate herpes zoster vaccine exists for shingles prevention); it may be used in older susceptible adults who lack evidence of immunity, based on physician assessment.
• Renal/hepatic impairment: no specific dose adjustment of Varivax is established for renal or hepatic impairment, as it is a biological immunizing agent rather than a systemically metabolized drug; individual immune status should still be assessed.
• Pregnant women: contraindicated - see Pregnancy and Lactation.

Varivax is not a continuous treatment but a preventive immunization given as a two-dose series at the intervals described in Dosage and Administration. No ongoing or repeated dosing of Varivax is required beyond the recommended two-dose schedule, unless updated public health guidance or a booster recommendation specifically advises otherwise.

Varivax is supplied as a lyophilized (freeze-dried) powder that must be reconstituted only with the sterile diluent provided by the manufacturer. Using a sterile syringe and needle, withdraw the entire volume of diluent and inject it into the vial containing the lyophilized Varivax powder. Gently agitate to dissolve completely.

The reconstituted Varivax should be a clear, colorless to pale yellow liquid; it should be inspected visually and discarded if particulate matter or discoloration is present. Administer immediately after reconstitution and discard any unused portion if not used within the time specified on the product label (typically 30 minutes). Do not freeze the reconstituted vaccine.

Vaccines > Viral Vaccines > Live Attenuated Vaccines > Active Immunizing Agents

Varicella Virus Vaccine contains a live, attenuated strain of varicella-zoster virus that, after subcutaneous injection, undergoes limited replication in the recipient. This controlled exposure stimulates the immune system to generate specific antibodies and cell-mediated (T-cell) immunity against varicella-zoster virus, mimicking the protective immune response of natural infection while avoiding significant clinical disease in immunocompetent recipients, thereby preventing or attenuating future varicella infection.

C (legacy FDA pregnancy category; contraindicated for use during pregnancy)

Varivax is approved for use in children 12 months of age and older. It is not recommended for infants younger than 12 months, as maternally-derived antibodies may interfere with the immune response, and safety and efficacy in this younger age group have not been established.

In healthy children 12 months to 12 years, Varivax is given as a two-dose series (first dose at 12-15 months, second dose at 4-6 years, per routine schedule); in those 13 years and older, two doses are given 4-8 weeks apart.