From the Guidelines
Acyclovir is not indicated for prophylactic use among otherwise healthy children, adolescents, or adults without evidence of immunity after exposure to varicella. The preferred method for post-exposure prophylaxis of varicella is vaccination, as stated in the recommendations of the advisory committee on immunization practices (ACIP) 1.
Key Points to Consider
- Vaccination is the method of choice for post-exposure prophylaxis in healthy individuals without evidence of immunity.
- For immunocompromised persons, varicella-zoster immune globulin (VZIG) is recommended due to the lack of studies on prophylactic use of acyclovir in this population 1.
- The use of acyclovir for post-exposure prophylaxis is not supported by evidence, and its role is more suited for the treatment of active varicella infection rather than prevention.
Clinical Decision Making
In clinical practice, the decision to use post-exposure prophylaxis for varicella should be based on the individual's risk factors and immune status. Vaccination should be prioritized for healthy individuals without evidence of immunity, while VZIG or alternative treatments should be considered for high-risk individuals, such as immunocompromised patients. It is essential to weigh the benefits and limitations of each approach, considering the potential risks and consequences of varicella infection in different populations.
From the FDA Drug Label
DOSAGE AND ADMINISTRATION Treatment of Chickenpox: Children (2 years of age and older):20 mg/kg per dose orally 4 times daily (80 mg/kg/day) for 5 days. Children over 40 kg should receive the adult dose for chickenpox Adults and Children over 40 kg: 800 mg 4 times daily for 5 days.
The answer to post-exposure prophylaxis of varicella with acyclovir is not directly addressed in the provided drug labels.
- Key points:
From the Research
Post-Exposure Prophylaxis of Varicella with Acyclovir
- The effectiveness of post-exposure prophylaxis with acyclovir for varicella is a topic of discussion in the medical community 3, 4, 5, 6.
- According to a study published in 2011, prophylactic acyclovir may be better than control treatment in preventing varicella, but the evidence is weak and the studies are small and not properly designed 3.
- A 2019 review suggests that post-exposure varicella vaccination may prevent infection or mitigate disease severity in persons eligible for vaccination, while post-exposure prophylaxis with varicella zoster immune globulin is indicated for populations ineligible for vaccination 4.
- A retrospective cohort study published in 2024 found that acyclovir was the most frequently prescribed post-exposure prophylaxis for varicella in high-risk children, but it was associated with a higher rate of subsequent encounters for varicella disease compared to varicella immunoglobulin and other treatments 5.
- Another study published in 2006 discusses the use of antiviral agents, including acyclovir, for the prevention and treatment of varicella zoster virus disease in immunosuppressed patients, but notes that there is no consensus on dose, duration, and patient population for its use 6.
- A 2018 systematic review found that the use of acyclovir in children and adolescents with varicella may not decrease associated complications, and it is unclear whether it reduces lesions or itching due to the low certainty of the evidence 7.
Key Findings
- Acyclovir may be used as post-exposure varicella prophylaxis in risk patients for whom the time window for VZIG-use has expired 3.
- The choice of varicella post-exposure prophylaxis regimens varies by underlying condition and institution 5.
- Post-exposure prophylaxis with varicella zoster immune globulin is indicated for populations ineligible for vaccination, including immunocompromised children and adults, pregnant women, newborns of mothers with varicella shortly before or after delivery, and premature infants 4.