Varicella (Chickenpox)

Key Information

• Disease: Varicella (chickenpox) is caused by the varicella-zoster virus (VZV). Reactivation of the virus results in herpes zoster (shingles).
• Complications: More common in adolescents, adults, and immunocompromised individuals.
• Vaccines Available: Univalent varicella vaccine and combined measles-mumps-rubella-varicella (MMRV) vaccine.
• Efficacy: 94.4% with one dose, 98.3% with two doses.

Recommendations for Use

• Routine Immunization:
  • Children (12 months to <13 years): Two doses of any varicella-containing vaccine.
  • Adolescents (13 to <18 years) and Adults (<50 years): Two doses of univalent varicella vaccine.
• Special Populations:
  • Immunocompromised Individuals: May receive the univalent varicella vaccine based on specific conditions.
  • Non-pregnant Women of Childbearing Age: Should prioritize varicella immunization.

Post-exposure Immunization

• Univalent Varicella Vaccine: Preferred for healthy, non-pregnant persons within 72 hours of exposure.
• Varicella Zoster Immunoglobulin (VarIg): Recommended for susceptible individuals at high risk of severe varicella, within 96 hours of exposure.

Authorized Vaccines in Canada

• Univalent Varicella Vaccines:
  • VARIVAX®III (Merck Canada Inc.)
  • VARILRIX® (GlaxoSmithKline Inc.)
• MMRV Vaccines:
  • PRIORIX-TETRA® (GlaxoSmithKline Inc.)
  • PROQUAD™ (Merck Canada Inc.)
• Varicella Zoster Immunoglobulin:
  • VariZIG™ (Cangene Corporation)

Adverse Events

• Common: Injection site reactions, low-grade fever, varicella-like rash.
• Rare: Febrile seizures, serious adverse events are very rare.

Administration Practices

• Dose: 0.5 mL, administered subcutaneously (SC) for univalent varicella vaccines.
• Concurrent Administration: Can be given with other vaccines, using different injection sites and separate needles.