Antibodies for people at high risk after chickenpox exposure
Varicella-zoster immunoglobulin
Antibodies given promptly to high-risk people after exposure to chickenpox or shingles to reduce how severe the infection becomes.
What is Varicella-zoster immunoglobulin?
Varicella-zoster immunoglobulin is a blood product containing ready-made antibodies against the chickenpox and shingles virus. It is given to people at high risk of severe illness, such as those who are pregnant, newborn babies or people with a weakened immune system, after they have been exposed to chickenpox or shingles. The most important point is that it is given promptly after exposure to reduce how severe the infection becomes. Supply is limited, so it is reserved for those most at risk, and antiviral medicines are sometimes used instead.
Education and reference only. This is a plain-language guide to Varicella-zoster immunoglobulin — 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
Varicella-zoster immunoglobulin is a preparation of antibodies, taken from human blood plasma, that act against the virus that causes chickenpox and shingles. It is used to protect people who are at high risk of becoming seriously ill if they catch chickenpox, such as those who are pregnant, newborn babies, and people whose immune systems are weakened. It is given after the person has been in contact with someone who has chickenpox or shingles and is not already protected. It is a blood product, given by injection, and is used as passive protection rather than as a vaccine.
How it works
Varicella-zoster immunoglobulin works by supplying ready-made antibodies that help fight the chickenpox virus, providing passive protection straight away rather than waiting for the body to make its own. Given promptly after exposure, these antibodies can reduce the chance of becoming seriously unwell or make the illness milder if it does develop. The effect is temporary, because the borrowed antibodies are gradually broken down. Because it is given to people who cannot safely have the vaccine and who are most at risk of harm, timing soon after exposure is important for it to work best.
Company & origin
Originated / developed by: Specialist manufacturers.
A blood product used in the UK to protect high-risk people who have been exposed to chickenpox or shingles.
Practical use
How to take Varicella-zoster immunoglobulin
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given by a healthcare professional, usually as an injection, as soon as possible after exposure to chickenpox or shingles.
- Tell the clinician straight away if you are at high risk and have been in contact with chickenpox or shingles, as early treatment matters.
- Let them know whether you have had chickenpox or the vaccine before, as this affects whether you need it.
- Still watch for signs of chickenpox afterwards and seek advice, as protection is not complete.
- Mention any previous reactions to blood products or injections before it is given.
Weighing it up
Advantages & disadvantages of Varicella-zoster immunoglobulin
Advantages
- Helps protect high-risk people from severe chickenpox after they have been exposed.
- Works straight away by supplying ready-made antibodies, which suits people who cannot have the vaccine.
- Can reduce the severity of the illness if given promptly after exposure.
Disadvantages
- Supply is limited, so it is reserved for those at highest risk.
- Protection is short-lived and not complete, so the illness can still occur.
- It is a blood product given by injection, and an antiviral medicine may be used instead in some cases.
Practical use
Good to know
The most important point is timing: this immunoglobulin is given promptly after exposure to chickenpox or shingles, because it works best when given early, before the illness has a chance to take hold. It is reserved for people at high risk of severe disease, such as those who are pregnant, newborns and people with a weakened immune system, because supply is limited and it is precious. For some people, an antiviral medicine is used instead of, or as well as, the immunoglobulin, depending on the situation and what is available. It is a blood product made from carefully screened and treated human plasma. Even after receiving it, you should still watch for signs of chickenpox and seek advice, as protection is not complete.
Who should not take it / use with caution
- People who have had a serious allergic reaction to a previous dose or to its ingredients should tell the clinician.
- It is used with care in people who have had reactions to blood products in the past.
- People who are already protected, having had chickenpox or the vaccine, usually do not need it.
Monitoring
- Watching for any allergic-type reaction during and shortly after the injection.
- Watching for signs of chickenpox developing afterwards, as protection is not complete.
- Reviewing whether an antiviral medicine is also needed, depending on the situation.
Side effects
- Soreness, redness or swelling where the injection is given, which usually settles.
- A mild raised temperature or feeling generally off-colour in some people.
- Rarely, allergic-type reactions, which is why it is given where help is available.
Key interactions
- It can reduce how well some live vaccines work, so the timing of certain vaccines may need to be spaced out.
- Tell the clinician about all vaccines you have had recently or are due to have.
- There are few other routine medicine interactions, but always share your full medicines list.
Available as: A solution for injection given by a healthcare professional.
Answers
Varicella-zoster immunoglobulin: frequently asked questions
What is varicella-zoster immunoglobulin used for?
It is given to people at high risk of severe chickenpox, such as those who are pregnant, newborns or people with a weakened immune system, after they have been exposed to chickenpox or shingles.
Why does it need to be given quickly?
It works best when given promptly after exposure, before the illness takes hold, which is why early contact with a clinician matters.
Why is it only for certain people?
Supply is limited, so it is reserved for those most at risk of becoming seriously unwell, particularly people who cannot safely have the vaccine.
Could I have an antiviral instead?
Yes, in some situations an antiviral medicine is used instead of, or as well as, the immunoglobulin, depending on the circumstances and what is available.
Will it stop me getting chickenpox?
It can reduce the chance of severe illness or make it milder, but protection is not complete, so you should still watch for signs of chickenpox and seek advice.
The wider class
About Human immunoglobulin (passive immunisation)
Varicella-zoster immunoglobulin belongs to the human immunoglobulin (passive immunisation) 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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