What is the recommended management for chickenpox?

Management of Chickenpox

For immunocompetent patients, oral acyclovir should be initiated within 24 hours of rash onset at 20 mg/kg (maximum 800 mg) four times daily for 5 days, with treatment prioritized for adolescents ≥12 years, adults, and those with chronic conditions, while immunocompromised patients require intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days. 1, 2

Primary Treatment Approach by Patient Population

Immunocompetent Patients

Children (<40-45 kg):

• Oral acyclovir 20 mg/kg per dose (maximum 800 mg) four times daily for 5 days 1, 2, 3
• Treatment must be initiated within 24 hours of rash onset for maximum clinical benefit 1, 4, 5
• Five days of therapy is sufficient; 7-day courses provide no additional benefit 1, 4

Adolescents (≥12 years) and Adults (>40-45 kg):

• Oral acyclovir 800 mg four times daily for 5-7 days 1, 2, 3
• Initiation within 24 hours of rash onset is critical—delayed treatment significantly reduces efficacy 1, 4
• Adults tend to have more severe disease and should be prioritized for treatment 6, 3

Alternative agent (Valacyclovir):

• Valacyclovir 20 mg/kg three times daily for 5 days (maximum 1 gram three times daily) is approved for children aged 2 to <18 years 7
• Not recommended for children <2 years as safety and efficacy are not established 7

Immunocompromised Patients

Critical distinction: Immunocompromised patients require intravenous therapy, not oral.

• Intravenous acyclovir 10 mg/kg every 8 hours for 7-10 days or until no new lesions appear for 48 hours 1, 2, 8
• Some experts recommend dosing based on body surface area in children >1 year: 500 mg/m²/dose IV every 8 hours 1
• Consider discontinuing immunomodulator therapy in severe cases if clinically feasible 8
• Dosage adjustment required for renal impairment 3

High-Risk Groups Requiring Antiviral Treatment

The following groups should receive acyclovir therapy even if immunocompetent:

• Adolescents ≥12 years and all adults 1, 2
• Patients with chronic cutaneous disorders (e.g., eczema) 1, 2, 8
• Patients with chronic pulmonary disorders 1, 2, 8
• Patients receiving long-term salicylate therapy (due to Reye syndrome risk) 1, 2, 8
• Patients on short, intermittent, or aerosolized corticosteroid therapy 1
• Secondary household contacts of infected children 1
• Pregnant women (though routine use is not generally recommended; acyclovir is Pregnancy Category B) 1, 3

Post-Exposure Prophylaxis

For Immunocompromised Patients:

• Varicella zoster immune globulin (VZIG) should be administered as soon as possible, ideally within 96 hours but up to 10 days after exposure 1, 2, 8
• If VZIG is unavailable, administer oral acyclovir 10 mg/kg four times daily for 7 days, starting 7-10 days after exposure 1, 2

For Pregnant Women:

• VZIG should be administered to pregnant women without evidence of immunity after exposure 1, 2

For Neonates:

• VZIG should be administered to neonates born to mothers with varicella 5 days before to 2 days after delivery 1, 2
• VZIG should be administered to premature infants <28 weeks gestation or <1,000 g regardless of maternal immunity 1, 2

For Healthy Individuals:

• Acyclovir is not indicated for prophylactic use in healthy individuals after exposure 1
• However, a 7-day course of acyclovir starting 7 days after exposure may be considered for those without access to vaccination 1, 8

Timing of Treatment Initiation: Critical Consideration

The evidence demonstrates a clear gradient in treatment efficacy based on timing:

• Maximum clinical benefit occurs when treatment is initiated within 24 hours of rash onset 1, 4, 5
• Treatment initiated on day 2 of rash shows some benefit but is significantly less effective than day 1 initiation 4
• Treatment initiated on day 3 of rash shows minimal benefit 4
• No data support treatment initiated >72 hours after rash onset 3, 7

Infection Control Measures

Patient Isolation:

• Isolate patients until all lesions have crusted over 1, 2, 8
• Patients are contagious from 1-2 days before rash onset until all lesions are crusted 6

Healthcare Worker Management:

• Healthcare workers without immunity exposed to VZV should be furloughed from days 10-21 after exposure (or days 10-28 if VZIG was administered) 6, 2
• Healthcare workers who received at least 1 dose of varicella vaccine and are exposed should be monitored daily during days 8-21 for fever and skin lesions 6
• Healthcare workers who received 2 doses of vaccine can continue working but should be monitored for breakthrough disease 6

Vaccination Considerations in Treatment Context

Contraindications:

• Live varicella vaccination is contraindicated in immunocompromised patients due to risk of disseminated infection 1, 2, 8

Household Contact Vaccination:

• Susceptible household contacts of immunocompromised patients should be vaccinated to prevent transmission 1, 2, 8

Timing After VZIG:

• Delay varicella vaccination 5 months after VZIG administration 1, 2

Post-Exposure Vaccination:

• Vaccination within 3-5 days of exposure may modify disease if infection has not yet occurred 6
• Vaccination >5 days post-exposure is still indicated for protection against subsequent exposures 6

Supportive Care

Symptomatic Management:

• Maintain adequate hydration 3, 7
• Antipyretics for fever (avoid aspirin in children due to Reye syndrome risk) 1
• Antihistamines for pruritus 9
• Antibiotics only if secondary bacterial skin infection develops 9

Important Clinical Caveats

Treatment Limitations:

• Acyclovir does not eradicate latent virus or affect subsequent risk, frequency, or severity of herpes zoster recurrences 1
• Antibody titers after infection in children receiving acyclovir do not differ substantially from untreated patients 1
• Acyclovir is not a cure for chickenpox 3, 7

Viral Resistance:

• Viruses shed during acyclovir therapy retain susceptibility to acyclovir and normal thymidine kinase function 4
• However, the effect on resistance of latent virus has not been assessed 4

Common Pitfalls:

• Do not rely on antibody titers in patients with nephrotic-range proteinuria or receiving IVIG, as they are unreliable 2
• Do not initiate treatment >72 hours after rash onset in immunocompetent patients, as efficacy is not established 3, 7
• Do not use corticosteroids routinely; their role remains controversial 9