What is the treatment and prevention for varicella zoster virus reactivation?

Treatment and Prevention of Varicella Zoster Virus Reactivation

The most effective strategy for preventing herpes zoster (shingles) and its complications is vaccination with the recombinant zoster vaccine (RZV), while acute herpes zoster should be treated with oral antiviral therapy (acyclovir, valacyclovir, or famciclovir) initiated within 72 hours of rash onset. 1

Understanding Varicella Zoster Virus

Varicella zoster virus (VZV) is a human neurotropic alphaherpesvirus that causes two distinct clinical entities:

• Primary infection: Varicella (chickenpox)
• Reactivation: Herpes zoster (shingles)

After primary infection, VZV becomes latent in sensory nerve ganglia along the entire neuraxis. When cellular immunity to VZV declines due to aging or immunosuppression, the virus can reactivate to cause herpes zoster 2.

Treatment of Acute Herpes Zoster

First-line Therapy

• Acyclovir: 800 mg orally 5 times daily for 7-10 days 3
• Valacyclovir: 1 gram 3 times daily for 7 days 4
• Famciclovir: 500 mg 3 times daily for 7 days

Treatment should be initiated at the earliest sign or symptom of herpes zoster and is most effective when started within 48 hours of rash onset 4, 3.

Special Populations

Immunocompromised Patients

• Intravenous acyclovir is indicated for immunocompromised patients with herpes zoster 1, 2
• Higher doses and longer duration may be required

Patients with Renal Impairment

Dose adjustments are necessary based on creatinine clearance:

Creatinine Clearance	Acyclovir Adjustment	Valacyclovir Adjustment
30-49 mL/min	800 mg every 8 hours	1 g every 12 hours
10-29 mL/min	800 mg every 12 hours	1 g every 24 hours
<10 mL/min	800 mg every 24 hours	500 mg every 24 hours

Complications Requiring Specific Treatment

• Postherpetic neuralgia: Tricyclic antidepressants, gabapentin, pregabalin, or topical lidocaine patches 2
• VZV vasculopathy: Intravenous acyclovir plus corticosteroids 5, 2
• Meningoencephalitis/myelitis: Intravenous acyclovir 2

Prevention of Herpes Zoster

Vaccination

Two types of herpes zoster vaccines are available:

1. Recombinant Zoster Vaccine (RZV, Shingrix)

   • Preferred vaccine due to higher efficacy (>90% across all age groups) 1, 6
   • Two-dose schedule
   • Recommended for adults ≥50 years of age
   • Can be used in immunocompromised patients 1, 6

2. Zoster Vaccine Live (ZVL, Zostavax)

   • Less effective than RZV
   • Single dose
   • Only for immunocompetent individuals when RZV is unavailable 1

Prophylaxis in High-Risk Populations

• Allogeneic HCT recipients: Antiviral prophylaxis (acyclovir, valacyclovir, or famciclovir) for at least 1 year post-transplant 1
• Autologous HCT recipients: Consider prophylaxis for 6-12 months post-transplant 1
• Patients on immunosuppressive therapy: Consider prophylaxis, especially for those receiving:
  • T-cell depleting agents (e.g., fludarabine)
  • Bortezomib or carfilzomib
  • Alemtuzumab (continue until 2 months after completion and CD4+ count ≥200 cells/mcL) 1

Approach to Different Patient Populations

Immunocompetent Adults

• Treatment: Oral antivirals for 7 days if within 72 hours of rash onset
• Prevention: RZV vaccination for adults ≥50 years

Immunocompromised Patients

• Treatment: Consider intravenous acyclovir for severe cases
• Prevention:
  • RZV vaccination when appropriate
  • Antiviral prophylaxis during high-risk periods

Patients with Inflammatory Bowel Disease

• RZV is the preferred vaccine, even for those on immunosuppressive therapy 1
• If RZV is unavailable, ZVL may be considered in patients on low-dose immunosuppression 1

Common Pitfalls and Caveats

1. Delayed treatment: Antiviral therapy should be initiated within 72 hours of rash onset for maximum effectiveness.

2. Inadequate pain management: Postherpetic neuralgia is a common complication that requires aggressive multimodal pain management.

3. Missing zoster sine herpete: VZV reactivation can occur without the characteristic rash, leading to neurological complications that may be misdiagnosed.

4. Overlooking vaccination: Many eligible adults remain unvaccinated against herpes zoster despite strong evidence for vaccine effectiveness.

5. Inadequate prophylaxis: High-risk immunocompromised patients often benefit from antiviral prophylaxis but may not receive it.

By implementing appropriate treatment and prevention strategies, the significant morbidity associated with herpes zoster and its complications can be substantially reduced.