Modelling the impact of vaccination on the epidemiology of varicella zoster virus in Australia.
OBJECTIVE
To model the impact of universal varicella vaccination in Australia.


METHODS
The results of an Australia-wide serosurvey for varicella zoster virus (VZV) immunity were used to parameterise realistic, age-structured deterministic models (RAS) developed by Brisson and colleagues. We examined the impact of a vaccination program for one-year-olds alone, and with a catch-up campaign for 11-year-olds, on the incidence of varicella and zoster, using Australia's population structure. Morbidity was then determined by calculating the number of hospital in-patient days.


RESULTS
Infant vaccination is predicted to reduce the incidence of varicella. However, zoster incidence is expected to increase initially, assuming exposure to varicella boosts immunity to zoster. Accumulated morbidity from both varicella and zoster is predicted to remain above that expected without vaccination for the first 70 years of an infant program (assuming 90% coverage with boosting for 20 years). However, after 70 years the net health savings from vaccination are predicted to increase substantially.


CONCLUSIONS
Infant vaccination is expected to be a successful long-term commitment to reducing morbidity associated with VZV infection in Australia.
Gidding
Heather F
HF
National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases, Royal Alexandra Hospital for Children and University of Sydney, New South Wales. heatherg@icpmr.wsahs.nsw.gov.au
Brisson
Marc
M
Macintyre
C Raina
CR
Burgess
Margaret A
MA
D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia / Q000453:epidemiology; D002644:Chickenpox / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D005260:Female; D014645:Herpesvirus 3, Human / Q000187:drug effects* / Q000276:immunology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D032541:Mass Vaccination; D008875:Middle Aged