What is the most appropriate management for a patient exposed to someone with active varicella (chickenpox) infection?

Post-Exposure Management for Varicella Contact

Immediate Recommendation

Administer varicella vaccine within 3-5 days of exposure (Option D) for susceptible individuals without contraindications, as this is >90% effective at preventing disease and is the preferred method for post-exposure prophylaxis. 1, 2

Risk Stratification Algorithm

The appropriate management depends critically on the patient's immunity status and risk category:

Step 1: Assess Evidence of Immunity

Evidence of immunity includes: 1, 3

• Documentation of age-appropriate vaccination (2 doses for most individuals)
• Laboratory evidence of immunity or confirmed prior disease
• Birth in the United States before 1980 (for non-healthcare workers who are not immunocompromised or pregnant)

Step 2: Management Based on Immunity Status

For Susceptible Immunocompetent Individuals (No Evidence of Immunity):

• Varicella vaccine within 3 days of exposure is the primary recommendation, with efficacy >90% for preventing disease 1, 2
• Vaccination may still provide benefit if given within 5 days of exposure 1, 3
• If exposure does not cause infection, vaccination provides protection against future exposures 1
• Reassurance alone (Option A) is inappropriate for susceptible individuals 2

For High-Risk Individuals with Contraindications to Vaccination:

• Varicella-zoster immune globulin (VZIG/VariZIG) within 96 hours (Option C) is indicated for: 1, 2
  • Immunocompromised patients (HIV, transplant recipients, cancer patients on chemotherapy)
  • Pregnant women without evidence of immunity
  • Newborns whose mothers developed varicella from 5 days before to 2 days after delivery
  • Premature infants
• VZIG provides maximum benefit when given as soon as possible, but may be effective up to 96 hours post-exposure 1
• The 2013 CDC guidelines extended this window to 10 days for certain high-risk populations 2

Step 3: Role of Acyclovir

Oral acyclovir immediately (Option B) is NOT indicated for post-exposure prophylaxis in otherwise healthy individuals. 2, 4

Key limitations of acyclovir for prophylaxis:

• Acyclovir is not recommended for prophylactic use after varicella exposure—vaccination is the method of choice 2
• Acyclovir is indicated for treatment of active disease, not prevention after exposure 4
• For treatment of chickenpox, acyclovir must be initiated within 24 hours of rash onset to be effective 2, 4
• Oral acyclovir dosing for chickenpox treatment (if disease develops): 800 mg four times daily for 5 days in adults, or 20 mg/kg four times daily in children 4

Post-Exposure Monitoring

For vaccinated individuals after exposure: 1

• Monitor daily during days 8-21 after exposure for fever, skin lesions, and systemic symptoms
• Exclude from work/school immediately if symptoms develop

For unvaccinated susceptible individuals: 5

• Exclude from institutions for 21 days after onset of rash in the last case
• Healthcare personnel should be excluded from duty from day 8 through day 21 after last exposure

Critical Pitfalls to Avoid

• Do not delay vaccination while awaiting serologic confirmation in individuals without clear evidence of immunity—vaccine within 3 days is critical 1, 3
• Do not use acyclovir for post-exposure prophylaxis in immunocompetent individuals—this is ineffective and not guideline-recommended 2
• Do not reassure and observe susceptible individuals without intervention—this misses the window for effective prevention 1, 2
• Do not administer VZIG beyond 96 hours unless in specific high-risk populations where extended window (up to 10 days) may apply 1, 2
• If varicella develops despite VZIG, institute antiviral therapy immediately 2

Special Populations

Pregnant women without immunity: 2

• VZIG is the intervention of choice (vaccination contraindicated during pregnancy)
• If varicella develops with complications like pneumonia, intravenous acyclovir is indicated

Immunocompromised patients: 2

• VZIG within 96 hours is critical
• If disease develops, immediate intravenous acyclovir (not oral) is required

Healthcare personnel: 1, 3

• Should be vaccinated when beginning employment as preferred strategy
• Post-exposure vaccination within 3-5 days if susceptible
• Strict exclusion protocols during days 8-21 post-exposure if unvaccinated