Chickenpox (varicella)

  • Key points

    1. Chickenpox is usually a self-limiting disease in immunocompetent children, requiring symptomatic treatment only
    2. Treatment with aciclovir is reserved for premature neonates or those <7 days of age, immunocompromised children, and children with systemic or central nervous system disease
    3. Varicella Zoster Immune Globulin (VZIG) should be given to an infant whose mother develops chickenpox 7 days before to 2 days after delivery, and to children at risk of complications of chickenpox


    • Chickenpox is caused by varicella-zoster-virus (VZV)
    • Exposed children should be considered infectious from 8-21 days post exposure, or 8-28 days if they have received Varicella Zoster Immunoglobulin (VZIG)
    • Children with chickenpox are infectious from 2 days before the appearance of rash until the vesicles are crusted over
    • Complications include bacterial superinfection, particularly group A Streptococcus (GAS) and S aureus, pneumonia, encephalitis, hepatitis, arthritis and Reye syndrome
    • Complications are more common in premature neonates and neonates exposed before 7 days of age, unimmunised adolescents and immunocompromised children
    • Recurrence of infection results in localised herpes zoster (shingles). In children, zoster can cross dermatomes, but is usually milder than in adults and post-herpetic neuralgia is less common
    • The National Immunisation Program currently includes a single dose of a varicella-containing vaccine (MMR-V) at 18 months of age
    • The Australian Technical Advisory Group on Immunisation (ATAGI) recommends that adolescents ≥14 years of age receive 2 doses of varicella vaccine, at least 4 weeks apart


    • Short prodrome of fever, lethargy and anorexia followed by eruption of rash over next 3-5 days


    • Crops of small papules, quickly become vesicular and then crust over after vesicles have ruptured
    • Usually fully crusted over by 10 days
    • May occur anywhere - scalp, face, trunk, mouth and conjunctivae are most typical locations
    • Lesions normally have significant surrounding erythema, particularly as they crust over - cellulitis tends to be over-diagnosed

    Vesicular lesions with erythematous margins. 
    Vesicular lesions with erythematous margins

    Rash later in course with many lesions crusting 
    Rash later in course with many lesions crusting

    Check vaccination status

    • Vaccine may cause a rash, typically 1-3 weeks later
    • Children who are immunised may still become infected with VZV, but the disease is typically mild

    Children at risk of complications

    • Malignancy
    • Receiving chemotherapy or high dose steroids (>20 mg/day prednisolone equivalent for 2 weeks)
    • Immunodeficiency


    • Encephalitis
    • Hepatitis
    • Pneumonia/pneumonitis



    • Chickenpox is a clinical diagnosis. No investigations are routinely required
    • In neonates or immunocompromised children, vesicular swab for VZV PCR may be helpful to confirm the diagnosis


    • In immunocompetent children >1 week old and <12 years old, no specific therapy is indicated
    • Avoid aspirin due to increased susceptibility to Reye syndrome
    • Avoid NSAIDs due to increased risk of invasive GAS
    • For bacterial superinfection, see Cellulitis and other bacterial skin infections
    • For underlying eczema, continue eczema treatment including topical steroids
    • Children must be excluded from school/kindergarten/childcare until all lesions crusted over
    • Avoid hospitalisation where possible. If required, isolation and contact precautions apply
    • VZV infection is a notifiable infection in some States. Contact local health department
    • Pregnant women who have had contact with chickenpox should be reviewed within 24 hours, regardless of the stage of pregnancy
    Consider IV aciclovir in the following cases
    • Premature neonates and term neonates <7 days of age (see neonatal section)
    • Children at risk of complications or with complications (see Assessment)
    Consider oral aciclovir in the following cases
    • Unvaccinated child age >12 years
    • Severe eczema
    • Chronic pulmonary disease
    • Children on salicylate therapy
    • Children on oral steroid therapy
    • Secondary cases in household contacts, as these are usually more severe

    Treatment of contacts

    • Neonates: see neonatal section below
    • Age 1 month-1 year: if not at risk of complications, observation is recommended. If at risk of complications (see Assessment), consider VZIG
    • Age >1 year: if within 5 days of exposure and no contraindications to vaccine, give VZV vaccine
      • There is no harm in having a second dose of VZV vaccine if immunisation status is uncertain or parents request this
      • If children are unable to have the vaccine and are at risk of complications, consider VZIG
      • Immunodeficient contacts should receive VZIG, and their household contacts should receive VZV vaccine if they are susceptible to disease

    Treatment and prevention of neonatal varicella infection

    • If a term neonate <1 week of age develops a rash consistent with chicken pox, they should be investigated and treated with IV aciclovir
    • Neonates who have had an exposure to VZV and subsequently become unwell, regardless of whether they received VZIG, should be commenced on IV aciclovir
    • Management of a neonate exposed to VZV depends on gestational age, mother’s serologic status and timing of the exposure. See table below for exposure management
    • If maternal serology is unknown, assume maternal antibodies absent  


    Antenatal maternal antibody (Ab) status


    Maternal chickenpox: born before 28 weeks

    No Ab transfer prior to delivery


    Maternal chickenpox: born after 28 weeks

    Maternal Ab present


    Maternal Ab absent


    Age <1 week at exposure (exposed from mother)

    Assume Maternal Ab absent


    Age <1 week at exposure (exposed from contact other than mother)

    Maternal Ab present


    Maternal Ab absent


    Other considerations for hospitalised neonates

    • Isolate a neonate who has had contact with VZV for the first 21 days of life (or 28 days if VZIG has been given)
    • Contact tracing should occur. If parents have been in contact with VZV, their immunity should be tested. If immune, they can attend the newborn nursery as normal
    • Other visitors who may have been exposed should be excluded from the nursery during the infectious period (8-21 days)
    • Maternal varicella is not a contraindication to breastfeeding. If the mother has lesions on her breasts, they should be covered with gauze and occlusive dressing

    Varicella Zoster Immune Globulin (VZIG)
    Doses are given IM according to the following table

    Weight of patient (kg)    

    Dose (IU)


    200 (1 vial)


    400 (2 vials)

    over 30

    600 (3 vials)

    • The dose of VZIG recommended in the table differs from that in the product information to minimise wastage
    • Normal human immunoglobulin can be used for the prevention of varicella if VZIG is unavailable
    • VZIG should be administered within 96 hours of exposure but can be effective if administered up to 10 days following exposure

    Consider consultation with local paediatric team when

    Any child meeting criteria for treatment with IV aciclovir or VZIG should be discussed with the local paediatric team

    Consider transfer when

    Child requiring care beyond the comfort of the local healthcare facility

    For emergency advice and paediatric or neonatal ICU transfers, see Retrieval services

    Parent information sheet

    Chicken pox

    Last Updated July 2021

  • Reference List

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