What is the management for individuals with a low or negative varicella (chickenpox) titer?

Management of Individuals with Low or Negative Varicella Titer

For persons who are known to be seronegative for varicella zoster virus (VZV), immunization with 2 doses of varicella vaccine with an interval of 4 weeks is recommended. 1

Assessment of Immunity Status

When evaluating individuals with low or negative varicella titers, consider:

• History of vaccination: Documented receipt of 2 doses of varicella vaccine supersedes results of subsequent serologic testing 1
• History of disease: While history of disease is helpful, some individuals with positive history might still be susceptible 1
• Immunocompromised status: Different approaches may be needed for immunocompromised individuals

Management Algorithm Based on Patient Population

For Immunocompetent Adults:

1. Seronegative adults (negative varicella IgG):

   • Administer 2 doses of single-antigen varicella vaccine 4 weeks apart 1
   • No routine post-vaccination serologic testing is recommended 1

2. Adults with low titers but prior vaccination:

   • If documented receipt of 2 doses exists, no further vaccination is needed regardless of titer results 1
   • If only 1 dose was received previously, administer second dose 1

For Healthcare Personnel (HCP):

1. Seronegative HCP:

   • Vaccination is particularly important to prevent nosocomial transmission 1
   • Administer 2 doses of varicella vaccine 4 weeks apart 1
   • Serologic screening before vaccination is cost-effective in healthcare settings 1

2. HCP with low titers after vaccination:

   • Commercial assays may not be sensitive enough to detect antibody after vaccination 1
   • Documented receipt of 2 doses supersedes negative serologic results 1

For Immunocompromised Individuals:

1. HIV-infected individuals:

   • For CD4 counts >200 cells/μL: Consider varicella vaccination (2 doses) 1
   • For severely immunocompromised: Avoid live vaccines; consider VariZIG after exposure 1

2. Patients with IBD on immunosuppressive therapy:

   • Ideally vaccinate before initiating immunosuppressive therapy 1
   • For those already on therapy, individual risk assessment is needed; consider infectious disease consultation 1

Special Considerations

Post-Exposure Prophylaxis:

• For susceptible individuals after exposure:
  • Varicella vaccine within 3-5 days of exposure may modify disease if infection occurred 1
  • For high-risk individuals with contraindications to vaccination: VariZIG within 10 days of exposure 1

Test Interpretation Challenges:

• Commercial ELISA assays may not detect lower antibody levels induced by vaccination 2
• Some individuals may have adequate cell-mediated immunity despite negative antibody titers 2
• More sensitive tests like fluorescent antibody to membrane antigen or latex agglutination may detect protection in those with negative ELISA results 2

Revaccination Response:

• Studies show that individuals with negative titers after initial vaccination often develop high antibody levels after revaccination, suggesting a booster effect 3, 4

Pitfalls to Avoid

1. Don't rely solely on history of disease: Up to 30% of adults with positive history might still be susceptible 1

2. Don't routinely test after vaccination: Commercial assays aren't sensitive enough to detect all vaccine-induced immunity 1

3. Don't assume negative titer equals susceptibility in previously vaccinated individuals: Cell-mediated immunity may provide protection despite negative antibody tests 2

4. Don't delay vaccination in susceptible individuals: Varicella can cause more severe disease in adults than children 5, 6