Yes, vaccinate adults who are seronegative for varicella with two doses of single-antigen varicella vaccine
All adults without evidence of immunity to varicella should receive 2 doses of single-antigen varicella vaccine administered 4–8 weeks apart 1, 2, 3. This is a clear, consistent recommendation across multiple ACIP guidelines spanning from 2007 to 2019.
Evidence of Immunity Definition
Before vaccinating, confirm the patient truly lacks immunity. Evidence of immunity includes 2, 3:
- Documentation of 2 doses of varicella vaccine at least 4 weeks apart
- U.S.-born before 1980 (except healthcare personnel and pregnant women—this exception does NOT apply)
- Healthcare provider-diagnosed or verified history of varicella or herpes zoster
- Laboratory evidence of immunity
If the patient is seronegative (non-reactive IgG) and has no other evidence of immunity, vaccination is indicated.
Dosing Schedule
- Adults ≥13 years: 2 doses of 0.5 mL single-antigen varicella vaccine subcutaneously, 4–8 weeks apart 1
- If more than 8 weeks elapse after the first dose, give the second dose without restarting the schedule 1
- Use only single-antigen varicella vaccine (VARIVAX), not MMRV, which is not licensed for persons >13 years 1
Priority Groups for Vaccination
Special consideration should be given to adults who 2, 3:
- Are healthcare personnel
- Have household contacts with immunocompromised persons
- Work in environments with likely VZV transmission (teachers, daycare employees, institutional settings, correctional facilities)
- Are college students or military personnel
- Are nonpregnant women of childbearing age
- Live in households with children
- Are international travelers
Immunogenicity and Efficacy
The vaccine is highly effective in seronegative adults. Research demonstrates:
- 82% seroconversion after one dose, 94% after two doses 4
- 94.3% seroconversion rate in initially seronegative subjects 5
- Protection against severe disease approaches 100%, even when breakthrough infections occur (which are typically mild with ~24 vesicles versus hundreds in natural infection) 4, 6
A critical caveat: Approximately 25% of vaccinees who initially seroconvert may lose detectable antibodies over time 4, 6. However, even those who become seronegative again retain partial protection, particularly against severe disease. This antibody waning is more pronounced in adults than children, with only ~70% maintaining detectable antibodies 2–6 years post-vaccination 6.
Safety Considerations
The vaccine is well-tolerated in seronegative adults 5:
- Local injection site reactions: 10–21%
- Mild rash: 6–8%
- Fever: uncommon
- No increase in reactogenicity when given to initially seropositive versus seronegative individuals 5
Contraindications 7:
- Pregnancy (counsel to avoid pregnancy for 3 months post-vaccination)
- Severe immunocompromising conditions
- Neomycin allergy
Special Populations
Immunocompromised patients: Generally contraindicated in highly immunocompromised individuals 8, 9. However, certain minimally immunocompromised patients (e.g., HIV with CD4 ≥200 cells/μL) may receive vaccination with a 3-month interval between doses 8, 9.
Healthcare workers: Vaccination is particularly important regardless of birth year before 1980, as this historical marker does not constitute evidence of immunity for this group 2, 3.
Women of childbearing age: Vaccinate if seronegative and not pregnant; administer first dose immediately postpartum if needed, with second dose 4–8 weeks later 2.
No Need for Pre-vaccination Serologic Screening
While this patient is already known to be seronegative, it's worth noting that routine pre-vaccination serologic screening is generally not recommended for immunocompetent adults ≥50 years in most guidelines 10. The high seroprevalence in adults and absence of safety concerns with vaccinating seropositive individuals make universal vaccination more cost-effective than screening.
Bottom line: A seronegative adult should receive the full 2-dose varicella vaccine series unless contraindicated. This provides substantial protection against varicella, particularly severe disease, and is safe and well-tolerated.