No Further Action Required
A positive varicella IgG antibody titer indicates immunity to varicella, so no postexposure prophylaxis or intervention is needed for this 70-year-old woman. 1
Rationale
The ACIP guidelines clearly establish that adults with positive varicella IgG antibodies are considered immune and do not require postexposure prophylaxis, regardless of exposure type or patient age 1. The decision to administer varicella-zoster immune globulin (VZIG) or other interventions depends on three critical factors:
- Whether the patient lacks evidence of immunity (this patient does NOT lack immunity)
- Whether the exposure is likely to result in infection
- Whether the patient is at greater risk for complications
Since this patient has documented positive IgG antibodies, she meets the criteria for "evidence of immunity" and the remaining two factors become irrelevant.
Key Management Points
No VZIG administration: VZIG is specifically indicated only for persons without evidence of immunity who are at high risk for severe complications 1, 2
No vaccination needed: Postexposure vaccination is recommended only for "unvaccinated persons without other evidence of immunity" 1
No monitoring required: Unlike healthcare personnel who received 2 doses of vaccine (who should be monitored days 10-21 post-exposure), immune individuals with positive serology do not require surveillance 1
Common Pitfall to Avoid
Do not confuse this scenario with bone marrow transplant recipients, who are the only exception to the rule that positive varicella history or serology indicates immunity. Bone marrow transplant recipients should be considered non-immune regardless of prior immunity 1. This patient has no indication of being a transplant recipient.
The positive IgG titer definitively establishes immunity, and the patient can be reassured that she is protected against varicella infection from this exposure.