Principal investigator 

Associate Professor Helen Marshall 

Varicella vaccine was included on the National Immunisation Program in 2005 for all children at age 18 months, with catch-up vaccination via school-based programs. PAEDS has been conducting surveillance for hospitalised varicella since 2007. Information is collected on complications of chickenpox (varicella-zoster virus infection) and children hospitalised with shingles (herpes zoster).

An important and unique aspect of this surveillance is that genotyping of the virus is also undertaken. Given that varicella has not been nationally notifiable in Australia, this surveillance has made an important contribution toward demonstrating the impact of the varicella vaccination program on severe disease.

In 2013, PAEDS published the first major study (Marshall et al, PIDJ 2013) to show a decline in hospitalised varicella and herpes zoster – estimated at 73% and 40%, respectively – since vaccine program commencement. In addition, all genotypes were ‘wild-type’ virus with no hospitalised cases due to any genotypes associated with the varicella vaccine. Of hospitalised children age-eligible for varicella vaccine, 80% were unimmunised, including all cases requiring intensive care. This reinforces the importance of vaccination.

Surveillance for varicella is ongoing. Most recently we identified that while vaccination provided some protection against more severe disease, breakthrough varicella requiring hospitalisation still occurs in some children vaccinated with a one-dose schedule,  providing evidence to support consideration of a 2-dose varicella vaccination schedule.