21 Varicella (chickenpox)

Key information

Mode of transmission Airborne droplets, or contact with infected respiratory tract secretions or vesicular lesions.
Incubation period Usually 14–16 days (range 10–21 days).
Period of communicability From 1 to 2 days before onset of the rash until all lesions have crusted.
Burden of disease Without immunisation, most people who reside in temperate climates have infection during childhood.

Groups at risk of severe complications include pregnant women and their unborn babies, and immune-compromised individuals.
Vaccines Varicella vaccines (Varilrix; Varivax) and MMRV vaccine (ProQuad) are live attenuated vaccines.
Recommendations and funding Recommended and funded (Varilrix) for certain high-risk groups and their contacts.

Recommended but not funded for all susceptible children, adolescents and adults.
Vaccine efficacy/effectiveness High after 1 dose, but 2 doses prevent outbreaks.
Contraindications Certain immune deficiency states – consult the child’s paediatrician for advice.

High-dose steroids.

Known systemic hypersensitivity to neomycin.

Active untreated TB.

Adverse events to vaccine Small increased risk of febrile seizures when MMRV is used for the first dose in toddlers.
Post-exposure prophylaxis Zoster immunoglobulin (ZIG) is most effective if given as soon as possible after exposure but may be given up to 10 days post exposure.

Varicella vaccine may be used for post-exposure prophylaxis if given within 5 days of exposure.