Indication: Vaccination against varicella (chickenpox) for individuals 12 months of age and older.
Revaccination: The need for booster doses is not well-defined, but a boost in antibody levels has been observed after exposure to wild-type varicella or after a booster dose administered four to six years post-vaccination.
Dosage and Administration
Pediatrics (12 months to 12 years): Single 0.5 mL dose administered subcutaneously.
Adolescents and Adults (13 years and older): Two 0.5 mL doses administered subcutaneously, 4 to 8 weeks apart.
Reconstitution:
Use only the supplied sterile diluent.
Inspect for particulate matter and discoloration before use.
Administer immediately after reconstitution, discard if not used within 90 minutes.
Route: Subcutaneous injection, preferably in the outer aspect of the upper arm (deltoid region).
Contraindications
Hypersensitivity to any component of the vaccine, including gelatin and neomycin.
Individuals with:
Blood dyscrasias, leukemia, lymphomas, or malignant neoplasms affecting bone marrow or lymphatic systems.
Immunosuppressive therapy or primary/acquired immunodeficiency states.
Active untreated tuberculosis.
Fever >38.5°C.
Pregnancy (and avoid pregnancy for three months post-vaccination).
Warnings and Precautions
General:
Avoid use of salicylates for 6 weeks post-vaccination due to the risk of Reye syndrome.
Adequate treatment provisions for anaphylactic reactions should be available.
Potential risk of transmission of vaccine virus to susceptible individuals.
Special Populations:
Pregnant Women: Not recommended; report any exposure during pregnancy.
Nursing Women: Unknown if virus is secreted in human milk.
Pediatrics: Not recommended for children under 12 months.
Immunocompromised: Not established for safety and efficacy.
Adverse Reactions
Common: Injection site pain, redness, swelling; fever; varicella-like rash.
Clinical Trials: Generally well-tolerated with mild to moderate adverse reactions. Rare cases of serious reactions reported.
Drug Interactions
Timing: Defer vaccination for at least 5 months post-transfusion or immune globulin administration.
Concurrent Vaccination: Can be administered with MMR, DTaP, and Hib vaccines at separate sites. Maintain a 1-month interval if not administered concomitantly.
Storage and Stability
Unreconstituted Vaccine: Store refrigerated at 2°C to 8°C or in the freezer at temperatures above -50°C. Protect from light.
Reconstituted Vaccine: Use within 90 minutes. Do not freeze reconstituted vaccine.
Diluent: Store at room temperature or refrigerated.
Clinical Trials and Efficacy
Children: Effective in preventing varicella, with protection lasting up to 9 years post-vaccination. Breakthrough cases were generally mild.
Adolescents and Adults: Two doses provided high seroconversion rates and long-term immunity.
Efficacy: 95-100% efficacy observed in clinical trials. Antibody levels correlated with reduced risk of breakthrough varicella.
