Chickenpox vaccine

Vaccinating your child against chickenpox is advised if they are in close contact with someone who is pregnant or who has a weakened immune system

Type of vaccine

Single live chickenpox vaccine

Protects against

Chickenpox

Primary course

2 doses at least one month apart

Boosters

None but an immunity blood test can be done to check

Suitable for ages

From 12 months

What is the chickenpox (Varicella) vaccine?

Chickenpox is a common childhood infection that causes a fever, skin rash and a breakout of fluid-filled blisters on the skin. A child usually only needs to catch it once to develop lifelong immunity.

In most cases, chickenpox is a mild illness and complications are rare but it can be more severe in adults, young infants or children with a weakened immune system. In the UK, approximately 20 people a year die as a result of chickenpox.

The chickenpox vaccine is designed to protect anyone vulnerable to the more severe complications associated with the illness.

Most people who have the vaccine will either not go on to catch chickenpox or will have a much milder version of the illness when they do come into contact with it.

How does the chickenpox vaccine work?

The chickenpox vaccine is made from a weakened strain of the varicella virus that causes the illness. Because the strain in the vaccine is weak, it teaches the immune system how to recognise and protect against the infection without giving the recipient full-blown chickenpox.

Who should have the chickenpox vaccine?

The chickenpox vaccine is most commonly recommended for children who are in close contact with someone with a weakened immune system – for example, a sibling or parent with leukaemia or who is undergoing chemotherapy.

Chickenpox can also be serious for unborn babies, so the vaccine may be recommended for children who are in close contact with someone pregnant who has never had chickenpox. The vaccine cannot be administered to anyone pregnant.

The vaccine can also be used to prevent chickenpox if given within five days of contact with someone who has the illness.

Chickenpox (Varicella) vaccine FAQs

Research shows that nine out of 10 children vaccinated with a single dose of the chickenpox vaccine develop immunity to the illness for around a year, after which protection drops off rapidly to around 62% long-term immunity.

Two doses of the vaccine have been shown to provide 94% long-term protection.

Of the two vaccines widely available, it appears that one, Varivax (which is the one we use most often at BabyJabs), may be significantly more effective.

The vaccination is not quite as effective after childhood. It’s estimated that 75% of teenagers and adults who are vaccinated will become immune to chickenpox.

Like all vaccines, the chickenpox vaccine can cause side effects. For the majority of people, they’re mild and self-resolve within a day or two.

Common side effects include pain and swelling at the injection site (approximately one in five children), fever and a mild chickenpox rash (approximately one in 10 children).

Like many other vaccines, it may cause occasional immune-related disorders such as erythema multiforme (a potentially life-threatening skin disorder), thrombocytopenia (a shortage of platelets in the blood causing bleeding problems), and neuropathies such as Guillain-Barré syndrome.

A severe allergic reaction (anaphylaxis) is extremely rare, being reported in approximately one in a million doses.

As the vaccine contains a live (though modified) virus, it can cause attacks of chickenpox in susceptible children, particularly those with immune deficiencies. In the same way that shingles can develop later in life in someone who has had chickenpox, shingles can also occur after vaccination; one would expect it to occur much less commonly after vaccination but, as the time lag between catching naturally occurring chickenpox and developing shingles is usually several decades, only time will tell.

As a live vaccine, the chickenpox jab should not be given to anyone with an impaired immune system, including those suspected of being HIV positive.

It is also not recommended during pregnancy.

The vaccine may not be suitable for your child if they:

  • Are allergic to any varicella vaccine, to any of the ingredients in this vaccine or neomycin (which may be present as a trace residue)
  • Have a blood disorder or any type of cancer that affects the immune system
  • Are receiving immunosuppressive therapy, including high doses of corticosteroids
  • Take medicine that weakens their immune systems
  • Were born with immunodeficiency or there is a family history of immunodeficiency
  • Have active untreated tuberculosis

The vaccine is given as two separate injections, usually into the thigh for children under five or upper arm for older children, four to eight weeks apart.

Two doses of the chickenpox vaccine provide long-lasting immunity in 94% of people.

The chickenpox vaccination can be given to children aged 12 months and older, adolescents and adults.

Varivax may also be administered to infants from nine months of age under special circumstances, such as to conform with national vaccination schedules or in outbreak situations.

Once your child has had two doses of the chickenpox vaccine, it shouldn’t need to be repeated.

If you or your child do want to check their level of immunity in the future, this can be investigated with an appropriate blood test that screens for antibodies.

The chickenpox vaccine may be recommended for adults who didn’t catch chickenpox as a child.

Yes, in most cases, the chickenpox vaccine may be given at the same time as other vaccines.

It can be given at the same time as an MMR vaccine or needs to be given a minimum of four weeks afterwards.

No, it’s not thought to be cost-effective to routinely vaccinate all children.

Yes, we can use the Varilrix vaccine as an alternative, as this is free from porcine gelatine. (See below for the Varilrix Patient Information leaflet below.)

Ingredients of the chickenpox vaccine

Manufacturer: Merck

Age: Suitable from 12 months

Active ingredients: Oka/Merck strain of varicella virus (produced in MRC-5 human diploid cells)

Other ingredients: Sucrose, hydrolysed gelatin, urea, sodium chloride, monosodium L-glutamate, anhydrous disodium
phosphate, potassium dihydrogen phosphate and potassium chloride. Residual components in trace quantities: neomycin.

Mercury content: Nil

Aluminium content: Nil

Contains porcine gelatin?: Yes

Contains dairy products?: No

Licensed for use in the UK

Varivax Patient Information Leaflet: Click to view

Manufacturer: GlaxoSmithKline UK

Age: Suitable from 12 months

Active ingredients: Varicella live attenuated virus (Oka strain, produced in MRC5 human diploid cells)

Other ingredients: Amino acids (containing phenylalanine*), lactose anhydrous, sorbitol (E 420), mannitol (E 421)

* This vaccine contains 331 micrograms of phenylalanine per dose. Phenylalanine may be harmful if your child has phenylketonuria (PKU), a rare genetic disorder in which phenylalanine builds up because the body cannot remove it properly.

Mercury content: Nil

Aluminium content: Nil

Contains porcine gelatin?: No

Contains dairy products?: Yes

Licensed for use in the UK

Varilrix Patient Information Leaflet: Click to view

Aftercare

We’ll give you detailed aftercare advice for your child after their vaccination(s), including what to do in the event of any side effects.

Your child may experience some redness, tenderness and/or swelling at the injection site, so it’s helpful to expect this. These side effects should self-resolve within a few days.

You can download our Patient Aftercare leaflet here.

If your child is unwell outside of clinic hours, please call 111 for advice or go to A&E if they need urgent medical attention.

Individual advice about the chickenpox (Varicella) vaccination

Need advice about whether your child should have the chickenpox vaccine? The BabyJabs team is here to listen and answer your questions to help you decide.