Introduction

The chickenpox (varicella) vaccine provides protection against the varicella zoster virus that causes chickenpox.

The chickenpox vaccine is not part of the routine childhood vaccination schedule. The vaccine is currently only offered to people who are particularly vulnerable to chickenpox.

The vaccine does not contain thiomersal (mercury).

Groups at risk from chickenpox
Chickenpox is a common childhood infection. In most cases the symptoms are mild and complications are rare. Almost all children develop immunity to chickenpox after infection, so only catch it once. The disease can be more severe in adults.

Certain groups of people are at greater risk of serious complications from chickenpox. These include people who have weakened immune systems through illness, such as HIV, or through treatment, such as chemotherapy.

Chickenpox can be very serious for an unborn baby when a pregnant woman catches the infection. It can cause a range of serious birth defects as well as severe disease in the baby when it is born.

How the vaccine works
The chickenpox vaccine contains a small amount of the live weakened varicella zoster virus. The vaccine causes your immune system to produce antibodies that will help protect against chickenpox.

The vaccine is recommended for individuals who are likely to come into contact with people in the 'at-risk' groups. This is to reduce the risk of the individuals spreading the infection to those at risk.

For example, if you were having chemotherapy treatment, it would be recommended that non-immune children be given the chickenpox vaccination. Or if you were about to start work in a radiotherapy department and you had no previous history of chickenpox, the vaccine would be recommended.

How effective is the vaccine
It has been shown that 9 out of 10 children vaccinated with a single dose will develop immunity against chickenpox. A two-dose schedule is now recommended for all, as it gives a better immune response. Three-quarters of teenagers and adults who are vaccinated will develop immunity against chickenpox.

When Chickenpox Vaccination Should be Given

When chickenpox vaccination should be given
If the chickenpox vaccination is required, two doses are given with four to eight weeks between the doses. The doses are injected underneath the skin.

Who should have it

Healthcare workers : The chickenpox vaccination is recommended for healthcare workers who have no previous history of chickenpox. If you are uncertain whether you have had chickenpox in the past, contact your doctor or occupational health department. A blood test will be used to check if you are immune to the disease.

Healthcare workers include anyone who is likely to come into contact with a patient, including medical and nursing staff and other workers such as:

• hospital cleaners
• hospital catering staff
• ambulance staff
• hospital

Close contact with vulnerable people : The chickenpox vaccination is also recommended for anyone who has no previous history of chickenpox and is likely to come into close contact with a person who has a weakened immune system. If you think that you or a member of your family or household needs a vaccination, contact your doctor for advice.

Who should not have it
People who have a weakened immune system should consult a doctor about whether or not they should have the vaccine.

The chickenpox vaccine should not be given to people who have experienced an anaphylactic reaction (serious allergic reaction) to a previous dose of the vaccine or to any of the ingredients used in the vaccine. If you are unsure whether this applies to you, ask your doctor.

The chickenpox vaccine should not be given to pregnant women. If you are receiving the vaccine, do not become pregnant for three months after the last dose.

Vaccination is not recommended for people who are seriously unwell. It should be delayed until they recover.

Side Effects of the Chickenpox Vaccine

The most common side effect of the chickenpox vaccine is soreness and redness around the site of the injection.

This side effect develops in around one in five children and one in four teenagers and adults. A mild rash may occur in 1 in 10 children and 1 in 20 adults.

Serious side effects, such as anaphylaxis (a serious allergic reaction), are rare. They occur in less than 1 in 100,000 vaccination cases.

Millions of doses of the vaccine have been given and there is no evidence of any increased risk of developing a long-term health condition as a result of the vaccination.

Frequently Asked Questions

Who should have the vaccination?
The chickenpox vaccination is not a routine childhood vaccination. It is only offered to individuals who are likely to come into contact with people who are particularly vulnerable to chickenpox (such as those having chemotherapy). This reduces the risk of chickenpox spreading to vulnerable people (see: When it is needed).

Why isn’t the chickenpox vaccination part of the routine childhood immunisation schedule?
Experts have been concerned that introducing chickenpox vaccination for children could increase the risks of shingles in older people. The advice has been to start with vaccination against shingles and then to think about chickenpox vaccination.

Shingles can be very damaging to the health of older people, as complications include:

• chronic nerve pain
• vision loss
• infection of the brain (encephalitis)

If people in ‘at risk’ groups cannot have the vaccine, what treatments are available if they catch chickenpox?
Chickenpox in people with weakened immune systems and pregnant women without immunity can be treated with a medication called varicella zoster immunoglobulin (VZIG).

VZIG contains chickenpox-virus-fighting antibodies, can reduce the severity and length of symptoms, and lower the risk of complications.

I have recently been vaccinated and have just found out that I am pregnant. What should I do?
If you find out that you are pregnant and you have been given a dose of varicella vaccine during the last three months, contact your doctor for advice.

A study in the US of nearly 700 women who had received the chickenpox vaccine while pregnant found no cases of babies affected by the vaccine.