Volume 183 - Issue 5
Universal varicella vaccination
Authors: Kristine Macartney and Peter McIntyre
Med J Aust 2005; 183 (5): 277-279. || doi: 10.5694/j.1326-5377.2005.tb07045.x
Published online: 5 September 2005
Published online: 5 September 2005
Kristine Macartney,* Peter McIntyre†
* Senior Research Fellow, † Director, National Centre for Immunisation Research, The Children’s Hospital at Westmead, Locked Bag 4001, Westmead, NSW 2145. petermATchw.edu.au
Comment: Recently published data have added considerably to the evidence about the impact of varicella vaccination programs, and address many of the concerns raised by Mackenzie.
First, in the United States where universal varicella vaccination was recommended a decade ago, recent data show that — despite much slower implementation than is expected in Australia — varicella-related disease has declined by up to 90%, and hospitalisation rates and deaths from varicella by more than two-thirds, due to herd immunity.1,2
Second, data have now been published on the incidence of herpes zoster in areas of sentinel surveillance in the US, showing no change in age-specific rates to 2002.3 Along with the success of a recent trial of high-dose varicella vaccine in reducing herpes zoster in older adults,4 these data add to confidence that any increase in herpes zoster — as predicted in some models — will be detected and effectively combated by vaccinating people aged over 60 years. A substantial allowance for surveillance of both varicella and herpes zoster was included in the 2005 federal budget, to accompany the introduction of universal varicella vaccination in Australia.
Mackenzie is correct that varicella is perceived by some as a mild illness, but it is important for general practitioners to emphasise to patients that this is incorrect.5 Each year in Australia, varicella causes around seven to eight deaths and more than 1500 hospitalisations,6 many associated with serious complications, such as invasive bacterial infection, pneumonia, and encephalitis. Although complications are more likely in adults and immunocompromised patients, 42% of hospitalisations are in children aged 0–4 years,6 most of whom are otherwise healthy.7
Patients can also be reassured about the safety of varicella vaccines, as clinical trials now date back 30 years, and more than 40 million doses of vaccine have been distributed in the US.
Mackenzie suggests alternatives to universal childhood varicella vaccination, such as vaccination of “high risk” patients and their families, or of adolescents alone. However, these programs would not prevent morbidity among otherwise healthy young children and older age groups, as they would be insufficient to generate herd immunity. Moreover, age-based vaccination strategies have been shown to be easier to implement than more targeted programs. In the absence of a publicly funded universal program, the private market could sustain modest varicella vaccination rates of around 40%–50% in Australia.8 This would increase the number of adolescents and adults susceptible to varicella, because of reduced exposure to the virus and lack of vaccination; these groups also experience greater morbidity with infection than children.
A universal program vaccinating young children and adolescents against varicella offers the best current option to reduce morbidity and mortality from this disease in Australia. Ongoing surveillance of varicella and herpes zoster in Australia and elsewhere will reveal whether there is a need for further interventions, such as a second dose of varicella vaccine in children and high-dose varicella vaccine to prevent herpes zoster in older adults.
References
- Davis MM, Patel MS, Gebremariam A. Decline in varicella-related hospitalizations and expenditures for children and adults after introduction of varicella vaccine in the United States. Pediatrics 2004; 114: 786-792.<eMJA full text>
- Nguyen HQ, Jumaan AO, Seward JF. Decline in mortality due to varicella after implementation of varicella vaccination in the United States. N Engl J Med 2005; 352: 450-458. 0_i1091556
- Jumaan AO, Yu O, Jackson LA, et al. Incidence of herpes zoster, before and after varicella-vaccination-associated decreases in the incidence of varicella, 1992-2002. J Infect Dis 2005; 191: 2002-2007. 0_i1091558
- Oxman MN, Levin MJ, Johnson GR, et al. A vaccine to prevent herpes zoster and postherpetic neuralgia in older adults. N Engl J Med 2005; 352: 2271-2284. 0_i1091560
- Taylor JA, Newman RD. Parental attitudes toward varicella vaccination. The Puget Sound Pediatric Research Network. Arch Pediatr Adolesc Med 2000; 154: 302-306. 0_i1091562
- Brotherton J, McIntyre P, Puech M, et al. Vaccine preventable diseases and vaccination coverage in Australia 2001 to 2002. Commun Dis Intell 2004; 28 Suppl 2: vii-S116. 0_i1091564
- Carapetis JR, Russell DM, Curtis N. The burden and cost of hospitalised varicella and zoster in Australian children. Vaccine 2004; 23: 755-761. 0_i1091566
- Marshall H, Ryan P, Roberton D. Uptake of varicella vaccine — a cross sectional survey of parental attitudes to nationally recommended but unfunded varicella immunisation. Vaccine 2005. In press. 0_i1091569