Varicella Vaccine Post-Exposure Prophylaxis

Introduction to Varicella Post-Exposure Prophylaxis

The Centers for Disease Control and Prevention recommends varicella vaccine administration to unvaccinated persons without evidence of immunity within 3 days of exposure for optimal protection (>90% efficacy), and can still provide benefit up to 5 days post-exposure (approximately 70% efficacy in preventing disease and 100% efficacy in preventing severe disease) 1, 2, 3

Within 3 days of exposure, varicella vaccine is >90% effective in preventing varicella entirely 1, 2, 3, 4, 5, 6, 7, 8
Within 5 days of exposure, varicella vaccine is approximately 70% effective in preventing varicella and 100% effective in modifying severe disease 1, 2, 3, 4, 5, 6, 7, 8

All unvaccinated persons without evidence of immunity should receive post-exposure vaccination, including children and adults 1, 2, 3, 4, 5, 6, 7, 8
The Advisory Committee on Immunization Practices (ACIP) recommends post-exposure vaccination for healthcare workers, though routine pre-exposure vaccination is the preferred prevention method 1, 2, 4, 5, 6, 7, 8

For persons with contraindications to vaccination who are at risk for severe disease, varicella-zoster immune globulin (VZIG/VariZIG) should be administered within 96 hours of exposure 1, 2, 3, 5

The ACIP recommends avoiding salicylates for 6 weeks post-vaccination due to Reye syndrome risk 1, 3, 4, 5, 6, 7, 8
Immune globulin interference: do not administer varicella vaccine for 3-11 months after receiving blood products or immune globulin, as passively transferred antibodies may inhibit vaccine response 4, 6, 7, 8
No evidence indicates increased adverse events when vaccine is given during presymptomatic or prodromal stages of infection 1, 2, 3, 9