Varicella Vaccination After Childhood Chickenpox
A patient with documented childhood varicella infection verified by a healthcare professional does not require varicella vaccination, as prior infection provides lifelong immunity and constitutes valid evidence of immunity. 1
Evidence of Immunity
The American Academy of Pediatrics defines three acceptable forms of evidence of immunity to varicella-zoster virus: 1
- Documentation of two appropriately timed varicella vaccine doses (evidence grade I) 1
- Laboratory evidence of immunity or laboratory confirmation of disease (evidence grade I) 1
- Varicella diagnosis by a healthcare professional or verified history of varicella disease (evidence grade III) 1
A history of herpes zoster diagnosed by a healthcare professional also satisfies evidence of immunity (evidence grade II-2). 1
Verification Requirements
For Typical Varicella Presentations
- Any qualified healthcare professional (school nurse, nurse practitioner, physician assistant, or physician) may verify immunity 1, 2
- Visual confirmation of a typical varicella rash during the acute illness is sufficient 2
For Atypical or Mild Presentations
- Verification must be performed by a physician or physician's designee 1
- Documentation must include either: 1
- An epidemiologic link to a typical varicella case or laboratory-confirmed case, OR
- Laboratory confirmation performed at the time of acute illness
Critical Distinction: Self-Report vs. Professional Verification
Parental self-report alone is insufficient and does not constitute valid evidence of immunity. 1, 2
The reliability of self-reported varicella history has declined significantly in the vaccine era: 2
- Pre-vaccine era: 97-99% of adults with positive varicella history were seropositive 2
- Vaccine era: Only ~75% of unvaccinated children aged 1-4 years who report prior infection are seropositive 2
This reduced reliability stems from lower disease incidence and increased mild breakthrough cases that are harder to recognize. 1, 2
Management When Documentation Is Lacking
If a patient reports childhood chickenpox but lacks healthcare professional verification or documentation, this does not constitute valid evidence of immunity. 2
In this scenario: 2
- The patient should receive the standard two-dose varicella vaccine series
- Other illnesses can mimic mild or atypical varicella, making verification essential 1
- Serologic testing may be performed to confirm immunity, though vaccination without testing is generally recommended 1
Serologic Testing Guidance
Serologic screening is generally not required or recommended when acceptable evidence of immunity is present. 1, 2
- Individuals lacking adequate documentation should be vaccinated without prior serologic testing 1, 2
- Post-immunization serologic testing is not advised because commercially available assays have limited sensitivity and may yield false-negative results 1, 2
- Exception: Serologic screening before vaccination may be cost-effective in adults with negative or uncertain history 3
Common Pitfalls to Avoid
- Do not accept parental report alone as evidence of immunity—healthcare professional verification is mandatory 1, 2
- Do not confuse exposure with infection—a history of exposure without documented disease does not constitute immunity 4
- Do not assume birth before 1980 equals immunity in healthcare personnel due to nosocomial transmission risks 3
- Do not mistake other exanthems for varicella—atypical presentations require epidemiologic linkage or laboratory confirmation 1
Vaccination Schedule for Those Without Evidence of Immunity
For individuals ≥13 years without documented immunity: 1