Why a chickenpox vaccine is now recommended and what we know about the dose schedule

The Health Information and Quality Authority (HIQA) has advised the Minister for Health to add a chickenpox vaccine to the schedule of childhood immunisation. Should parents be concerned about this and when is the vaccine likely to be introduced?

Q. The vaccine is actually against the varicella zoster virus. How is this linked with chickenpox?

A. Varicella is a common, highly infectious disease caused by the varicella zoster virus (VZV). VZV is associated with two distinct clinical syndromes: varicella, commonly known as chickenpox; and herpes zoster, commonly known as shingles.

Primary infection with VZV results in chickenpox, after which the virus hides out in the body’s nervous system. The virus may reactivate after a period, sometimes several decades later, resulting in a separate disease, shingles.

Q. I thought chickenpox was a mild disease that causes a skin rash and not much else? Why do we need a vaccine against it?

Chickenpox is a common, highly infectious disease mainly affecting children less than 10 years old. While most children are only unwell for a short period, chickenpox can result in long-term skin scarring and, less commonly, serious complications such as pneumonia and infection of the central nervous system.

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Of the 58,000 cases of chickenpox every year in Ireland, about one in 250 cases will be hospitalised with complications. And approximately one third of people who have had chickenpox will develop shingles later in life due to reactivation of the virus. For older people shingles has the potential to cause a painful condition called post-herpetic neuralgia, which affects mood, sleep and quality of life.

Q. How safe is the vaccine?

A. Very safe. A vaccine for chickenpox has been available for over 30 years. The vaccine is currently offered as part of the childhood immunisation programmes in several countries, including Canada, Australia and New Zealand.

Q. What’s the recommended dose of the vaccine?

Hiqa has suggested two options for the Department of Health to consider. One dose of the vaccine will reduce severe disease, including the hospitalisation of children who develop chickenpox. Two doses have the potential to further reduce the number of cases and eliminate chickenpox. A one-dose regimen would be given to children aged 12 months. If a two-dose vaccine strategy is chosen, the second dose is likely to be administered at five years.

Q. When is the vaccine likely to be included in the childhood immunisation scheme?

A. Today’s assessment was requested by the Department of Health following a policy recommendation from the National Immunisation Advisory Committee (NIAC). Once a decision is made between a one- or two-dose vaccine schedule, a formal go-ahead should be quick. Then it is a matter for the HSE’s National Immunisation Office to put practical arrangements in place to allow chickenpox vaccine to be given to infants by general practitioners and, in the case of two-dose schedule, for the schools health service to administer the follow-up shot.

Hiqa found that there is clear and consistent evidence that the chickenpox vaccine is both safe and effective in preventing chickenpox and its complications. It’s health technology assessment (HTA), published today, concluded that adding the chickenpox vaccine to the childhood immunisation programme is likely to be cost effective.