varicella virus vaccine, live
Varivax

Available forms
Available by prescription only
Injection: Single-dose vial containing 1,350 plaque-forming units of Oka/Merck varicella virus

Indications and dosages
 Prevention of varicella-zoster (chickenpox) infections. Adults and children age 13 and older: Administer 0.5 ml S.C.; then give a second dose of 0.5 ml 4 to 8 weeks later.
Children ages 1 to 12: 0.5 ml S.C. as a single dose.

Pharmacodynamics
Antiviral vaccine action: Prevents chickenpox by inducing production of antibodies to varicella-zoster virus.

Pharmacokinetics
Absorption: Administered S.C.
Distribution: No information available.
Metabolism: No information available.
Excretion: No information available.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug, in pregnant women, in patients with history of anaphylactoid reaction to neomycin, and in patients with blood dyscrasias, leukemia, lymphomas, neoplasms affecting bone marrow or the lymphatic system, primary and acquired immunosuppressive states, active untreated tuberculosis, or any febrile respiratory illness or other active febrile infection.

Interactions
Drug-drug. Blood products, immune globulin: May inactivate vaccine. Defer vaccination for at least 5 months after blood or plasma transfusions or administration of immune globulin or varicella-zoster immune globulin.
Immunosuppressants: Increases risk of severe reactions to live-virus vaccines. Postpone routine vaccination.
Salicylates: Causes risk of developing Reye’s syndrome. Avoid salicylates for 6 weeks after vaccination.

Adverse reactions
CNS: fever.
Skin: varicella-like rash.
Other: injection site reactions (swelling, redness, pain, rash).

Effects on lab test results
None reported.

Overdose and treatment
No information available.

Special considerations
 ALERT Have epinephrine readily available.
• Administer vaccine immediately after reconstitution. Discard if not used within 30 minutes.
• Vaccine contains a live attenuated virus. Children who develop a rash may be capable of transmitting virus.
• Vaccine has been safely and effectively used with measles, mumps, and rubella vaccine.
• Vaccine appears to be less effective in adults than in children.
• Studies are underway to determine how often herpes zoster occurs after a latent period.
• Pregnancy should be avoided for 3 months after receiving vaccine.
• Monitor patient for rash; patient may be capable of transmitting virus.
• Antibodies usually noted 4 to 6 weeks after S.C. injection. Varicella antibodies have been detected 99.5% of the time 4 years postvaccination.
Breast-feeding patients
• It isn’t known if vaccine virus appears in breast milk. Use cautiously in breast-feeding women.
Pediatric patients
• A safety study protocol program is available for children and adolescents (ages 12 to 17) with acute lymphocytic leukemia. Clinicians can enroll patients in this program by contacting Omnicare Clinical Research, Inc.
• Safety and efficacy in children younger than age 1 haven’t been established.

Patient education
• Inform patient or parents about adverse reactions associated with vaccine.
• Caution woman of childbearing age to call if pregnancy is suspected before receiving vaccine.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use