Varicella Vaccination for Adults
Adults aged ≥13 years without evidence of varicella immunity should receive two 0.5-mL doses of single-antigen varicella vaccine administered subcutaneously, 4-8 weeks apart. 111
Vaccination Schedule
The ACIP guidelines are clear and consistent on the adult varicella vaccination regimen:
- Two doses required for all adults ≥13 years without immunity
- Route: Subcutaneous administration
- Dose: 0.5 mL per dose
- Interval: 4-8 weeks between doses (minimum 4 weeks) 111
- Flexibility: If more than 8 weeks elapse after the first dose, the second dose may be administered without restarting the schedule 11
- Formulation: Only single-antigen varicella vaccine (VARIVAX) is approved for adults; MMRV is NOT licensed for persons ≥13 years 11
Catch-Up Vaccination
For adults who previously received only one dose, the minimum interval for the catch-up second dose is 4 weeks, though it may be administered at any interval longer than this minimum 11
Priority Groups for Vaccination
While all healthy adults without immunity should be vaccinated, special consideration and priority should be given to 111:
- Healthcare personnel
- Household contacts of immunocompromised persons
- Teachers and day-care employees
- Residents and staff in institutional settings
- College students, inmates, and military personnel
- Nonpregnant women of childbearing age
- Adults living in households with children
- International travelers
Contraindications
Absolute contraindications per FDA labeling 2:
- Pregnancy (live virus vaccine; can cause congenital varicella syndrome)
- Severe allergic reaction to any vaccine component (neomycin, gelatin) or previous varicella vaccine dose
- Immunosuppression
- Moderate or severe febrile illness
- Active untreated tuberculosis
Critical Pregnancy Considerations
- Prenatal assessment for varicella immunity is mandatory 11
- Birth before 1980 is NOT considered evidence of immunity for pregnant women due to potential severe fetal consequences 1
- Postpartum vaccination protocol: Women without immunity should receive the first dose before hospital discharge, with the second dose 4-8 weeks later (coinciding with postpartum visit) 1
- A pregnancy registry (1995-2013) showed no increased risk of congenital varicella syndrome after inadvertent vaccination, though the vaccine remains contraindicated 2
Important Drug Interactions and Precautions
- Avoid salicylates for 6 weeks after vaccination due to Reye syndrome risk 22
- Immune globulins and blood products may interfere with vaccine response 2
- Tuberculin skin testing should be performed before vaccination, on the same day, or at least 4 weeks after 2
- Spacing with other live vaccines: If not given concurrently, wait at least 1 month between live attenuated measles-containing vaccines and varicella vaccine 2
Common Pitfalls to Avoid
- Do not assume birth before 1980 equals immunity in pregnant women - this is a critical exception to the general rule 1
- Do not use MMRV in adults - only single-antigen vaccine is licensed for ≥13 years 11
- Do not delay the second dose unnecessarily - while 4-8 weeks is recommended, completion rates drop with longer intervals
- Do not forget to assess immunity first - vaccination is only for those without evidence of immunity (prior disease, vaccination, or serologic confirmation)
Evidence of Immunity
Before vaccinating, assess for evidence of immunity through:
- Documentation of two doses of varicella vaccine
- Laboratory evidence of immunity or disease
- Birth in the United States before 1980 (except for pregnant women, healthcare personnel, and immunocompromised persons)
- Healthcare provider diagnosis or verification of varicella or herpes zoster
The two-dose regimen provides superior protection compared to single-dose schedules, with research showing significant waning of protection after only one dose 3. The 4-8 week interval balances immunogenicity with practical completion rates, as studies demonstrate high seroconversion even with flexible scheduling 4.