Some Questions and Answers about Chickenpox
What is Chickenpox?
Chickenpox is one of the childhood infectious diseases. It is caused by the varicella zoster virus, which also causes shingles. As with all childhood infectious diseases, it is more serious if contracted in adulthood. In childhood the child is unwell with a fever (high temperature) and blistering lesions which can occur all over the body. It is most common in children under 10 and is most prevalent in the winter and spring months.
What are the complications of Chickenpox?
Complications include pneumonia, bleeding problems, inflammation of the brain (encephalitis), meningitis, myocarditis (inflammation of the heart).
What about pregnant women?
If a woman comes into contact with chickenpox or shingles when pregnant, there is no problem if she has had it before, because it makes the body immune to it (re-infection is rare). This means the baby is not at risk of chickenpox even if the mother develops shingles during pregnancy.
If the woman has not had chickenpox before, or is unsure if she has, she should see her GP to be tested for it. If this shows she has not had chickenpox and has no antibodies, then chickenpox antibodies can be given. This is best given within 4 days (but can be given up to 10 days) of coming into contact with the chickenpox virus.
If a pregnant woman contracts chickenpox she has a 10% chance of getting chickenpox pneumonia, which can be severe. If the woman contracts chickenpox in the first 20 weeks of pregnancy the fetus has between a 0.4 and 2% risk of chickenpox syndrome with multiple abnormalities.
What is Shingles?
Shingles is an infection of a nerve and the area of skin that is supplied by it. It (Shingles) is caused by the herpes varicella-zoster virus which also causes chickenpox.
Most people have chickenpox as a child, but after the illness has gone, the virus remains dormant (inactive) in the nervous system. If the virus reactivates in the spinal chord it causes Shingles. About 1 in 5 people get Shingles at some point in their life. Although it can occur at any age, it is most common in people over 50. Shingles usually affects the nerve supply on one side of the body. The main symptoms are pain and a rash. The pain can continue for months.
How does the Chickenpox vaccine work?
Varilrix contains live, weakened varicella-zoster virus, which is the cause of chickenpox. This specially weakened virus is called the Oka Strain. It also contains inactive ingredients – amino acids, human albumin, lactose, neomycin sulphate, sorbitol and mannitol.
Why is the virus weakened?
It is weakened so that it does not cause Chickenpox in normal, healthy people.
When is Chickenpox vaccination given?
Chickenpox vacciantion is particularly useful to prevent Chickenpox in people who did not get the illness in childhood. Chickenpox is a much more severe infection when a teenager or in adulthood.
What about children?
Healthy children between 1 and 12 years of age can be vaccinated to prevent them catching Chickenpox, especially if it prevents them passing the disease onto someone for whom it could be serious (eg a weak immune system or pregnant).
How long does it take to develop immunity to Chickenpox?
98.7% of children have good immunity by 6 weeks after vaccination. Whether a booster to ensure immunity into adult hood will be required is not known at the present time.
If I am vaccinated can I pass on Chickenpox?
In healthy people less than 1 in 10,000 people pass on the vaccine virus to others. This can only happen when the vaccinated person develops spots or blisters, usually at the site of the injection.
How is Chickenpox vaccine given?
The vaccine is injected under the skin (subcutaneously) in the upper arm.
What is the programme for vaccination?
The WellCare programme for Chickenpox vaccination is:
| 12 months to 12 years |
1 vaccination |
Adults and adolescents from 13 years 2 vaccinations at 8 week
intervals.
Whether boosters will become necessary for children is uncertain.
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