A live vaccine that protects against chickenpox
Varicella vaccine
A live vaccine that protects against chickenpox (varicella).
What is Varicella vaccine?
The varicella vaccine protects against chickenpox, a common infection that is usually mild in children but can be serious in some people, such as those with a weakened immune system. It is a live vaccine, meaning it contains a weakened form of the virus, so it must not be given to people who are significantly immunosuppressed or who are pregnant. In the UK it is offered to certain groups rather than to all children, for example some healthcare workers and close contacts of vulnerable people. Side effects are usually mild, such as soreness where the injection is given or a mild rash. Follow the UK health service advice on who should have it.
Education and reference only. This is a plain-language guide to Varicella vaccine — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
The varicella vaccine is an immunisation that protects against chickenpox, an infection caused by the varicella-zoster virus. Chickenpox is usually mild in healthy children but can cause serious illness in some people, including those with a weakened immune system, newborn babies and, sometimes, adults. The vaccine contains a weakened live form of the virus. In the UK it is not part of the routine childhood schedule for everyone, but is offered to certain groups, such as some healthcare workers who are not already immune and people in close contact with those at high risk.
How it works
The varicella vaccine contains a weakened live form of the chickenpox virus that is strong enough to prompt the immune system to make protective antibodies but too weak to cause the full illness in healthy people. After vaccination, the immune system is primed so that if the person later meets the real virus, it can respond quickly and either prevent chickenpox or make it much milder. Because the virus in the vaccine is live, the immune system needs to be able to handle it safely, which is why it is not suitable for people who are significantly immunosuppressed.
Company & origin
Originated / developed by: Various manufacturers.
A live vaccine used in the UK to protect against chickenpox, offered to certain people such as some healthcare workers and close contacts of those at risk.
Practical use
How to take Varicella vaccine
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- Have it only if it is recommended for you, following UK health service advice on which groups should be vaccinated.
- Tell the nurse or doctor if you are, or might be, pregnant, as this live vaccine is not given in pregnancy.
- Tell the team about any condition or medicine that weakens your immune system, as the vaccine may not be suitable.
- Have both recommended doses, spaced as advised, for the best protection.
- Expect possible mild soreness or a mild rash; rarely you may be asked to avoid very vulnerable people for a short time.
Weighing it up
Advantages & disadvantages of Varicella vaccine
Advantages
- Protects against chickenpox, which can be serious in some people.
- Helps protect vulnerable people indirectly when their close contacts are vaccinated.
- Provides good protection after the recommended course, usually two doses.
Disadvantages
- It is a live vaccine, so it cannot be given to people who are significantly immunosuppressed or pregnant.
- Can cause a mild chickenpox-like rash and, rarely, the need to avoid very vulnerable people for a while.
- Usually needs two doses for good protection.
Practical use
Good to know
The most important point about the varicella vaccine is that it is a live vaccine: it contains a weakened form of the virus, so it must not be given to people who are significantly immunosuppressed (for example by certain illnesses or medicines such as high-dose steroids or chemotherapy) or to women who are pregnant, and pregnancy should be avoided for a period after vaccination as advised. In the UK it is offered to specific groups rather than to all children, such as some healthcare workers who are not already immune and close contacts of people who are vulnerable to severe chickenpox. Side effects are usually mild, such as soreness where the injection is given or a mild chickenpox-like rash; rarely, the rash means the vaccinated person should take care around very vulnerable people for a while. Two doses are usually needed for good protection.
Who should not take it / use with caution
- People who are significantly immunosuppressed should not have it, because it is a live vaccine.
- Women who are pregnant should not have it, and pregnancy should be avoided for a period afterwards as advised.
- People who have had a serious allergic reaction to a previous dose or a vaccine ingredient should not have it.
- If you are unwell with a high temperature, vaccination may be delayed until you are better.
Monitoring
- Checking it is suitable for you, particularly your immune status and whether you could be pregnant.
- A short period of observation after the injection in case of an immediate reaction.
- Ensuring both recommended doses are given for full protection.
Side effects
- Soreness, redness or swelling where the injection is given.
- A mild temperature or feeling generally off for a short time.
- A mild chickenpox-like rash a week or two after the injection.
- Very rarely, a serious allergic reaction soon after vaccination, which staff are trained to manage.
Key interactions
- Other live vaccines may need to be given at the same time or spaced apart, as your team advises.
- Medicines that weaken the immune system can make this live vaccine unsuitable, so tell the team about them.
- Avoid certain medicines, such as aspirin in children, for a period after vaccination if advised, and follow your team's guidance.
Available as: An injection, usually given into the upper arm, after the live vaccine is made up.
Answers
Varicella vaccine: frequently asked questions
What does the varicella vaccine protect against?
It protects against chickenpox, which is usually mild in children but can be serious in some people, such as those with a weakened immune system.
Why can't everyone have it?
It is a live vaccine, so it must not be given to people who are significantly immunosuppressed or pregnant; in the UK it is offered to certain groups rather than to all children.
Can I have it if I am pregnant?
No. It is a live vaccine and is not given during pregnancy, and pregnancy should be avoided for a period after vaccination as your team advises.
How many doses do I need?
Two doses are usually needed, spaced as advised, to give good protection against chickenpox.
What are the common side effects?
They are usually mild, such as soreness where the injection is given or a mild chickenpox-like rash a week or two later.
The wider class
About Live vaccine (chickenpox protection)
Varicella vaccine belongs to the live vaccine (chickenpox protection) class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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