| Category | Details |
|---|---|
| Risk of hospitalisation | Pre vaccine – all ages : approx 1 in 57,000 (0.002) ; under 5s : approx 1 in 9,000 (0.01%) |
| Risk of death | Pre vaccine (2024) – All ages : approx 1 in 4 million (0.00003%); Zero deaths in under 5s since 2000 |
What is Chickenpox?
Chickenpox is a common, mild, and highly contagious illness that primarily affects children but can occur at any age. Medically known as varicella, it is caused by the varicella-zoster virus. The infection is more prevalent in winter and spring, especially between March and May. Chickenpox presents as a red, itchy rash that develops into fluid-filled blisters, which eventually crust over and form scabs that fall off. New spots may continue to appear in waves over 3 to 5 days after the rash begins. Before the rash appears, mild flu-like symptoms, such as nausea, a fever of 38°C or higher, muscle aches, headaches, loss of appetite, and general discomfort may occur. These symptoms, particularly fever, tend to be more severe in adults than in children. Chickenpox is contagious from about two days before the rash starts until all blisters have crusted over. After recovering, the virus remains dormant in the nervous system and can reactivate later in life as shingles.
For most children, chickenpox is a mild illness that resolves on its own, with complications being rare and more likely to affect adults. Chickenpox parties were common not so long ago, where parents deliberately exposed children to the virus to have them contract the disease at a younger, less risky age and build immunity.
Well nourished children have little to fear from chicken pox and perhaps something to gain. This study from the University of Berne, Switzerland [Introduction – 4] reviewed these fever inducing (i.e. febrile) infections and concluded “study consistently revealed a lower cancer risk for patients with a history of FICD [febrile infectious childhood diseases].”
What is the risk of hospitalisation from chickenpox in Ireland?
The risk of hospitalisation from chickenpox for under 5s is approximately 1 in 9,000 (0.01%). Cases in the table below include both confirmed and suspected cases of chicken pox. There is no data for admission to intensive care units.
What is the risk of death from chickenpox in Ireland?
The risk of death from chickenpox in Ireland has always been very low. In the decade 2012 to 2021, the risk of death was approximately 1 in 4 million (0.00003%) for all ages. All of these deaths were in those aged over 70. There were zero deaths for under 5 year olds in this period.
What vaccine is recommended in childhood schedule for chickenpox in Ireland?
Varivax, manufactured by Merck Sharp & Dohme was introduced in 2024 to vaccinate against chicken pox. Despite the low risk chickenpox presents to children, the HSE added the chickenpox vaccine to the routine childhood vaccination schedule in 2024, to counter societal costs such as “leave from paid work to care for sick children”. The HSE recommend two doses for babies at 12 months and in junior infants.
Does the Varivax vaccine guarantee protection against chickenpox?
No. As with all vaccines and as stated on the patient information leaflet, protection from the disease cannot be guaranteed. Chickenpox type rash is listed as a common side effect on the patient information leaflet, affecting 1 in 10 people.
This study on Vaccination to prevent Varicella from Sage Journals 2013 stated the following:
When the costs of the booster dose for varicella and the increased shingles recurrences are included, the universal varicella vaccination program is neither effective nor cost-effective.
Summary of risks from Varivax vaccine
Click here to see full details on the varivax vaccine
| Risks from each dose of chickenpox Varivax vaccine |
|---|
| 2 doses recommended, at 12 months and in junior infants (Side effects as per Varivax patient information leaflet Dec 2023) |
| Observed side effects post administration of Varivax (post marketing) |
|---|
|
| Risk Category | Observed Side Effects |
|---|---|
| Up to 1 in 10,000 (0.01%) |
|
| Up to 1 in 1,000 (0.1%) |
|
| Up to 1 in 100 (1%) |
|
| Up to 1 in 10 (1% to 10%) |
|
| Some other special warnings and precautions |
|---|
| Should not be given if child is allergic to antibiotic neomycin |