Chickenpox (varicella) is caused by the varicella-zoster virus (VZV) and it is a highly infectious disease that usually causes an itchy red rash with blisters. It is commonly a childhood disease, although it can affect adults as well. Most people recover fully from chickenpox, but it can cause complications. A child with chickenpox can miss up to two weeks of school.
Immunisation against chickenpox is included in the combination measles, mumps, rubella and varicella (MMRV) vaccine recommended for children at 18 months of age. (The chickenpox vaccine is no longer offered to 12--13 year old adolescents in Year 7 of secondary school because these children had their dose at 18 months of age).
Complications of chickenpox
Most people recover fully from chickenpox without ongoing problems, but it can cause complications in some adults and children and in people who have weakened immune systems. The complications may include:
- scarring -- chickenpox can leave pockmark scars on the skin
- cellulitis -- a type of bacterial infection of the skin
- pneumonia -- infection and inflammation of the lung can occur in adults and can be fatal
- encephalitis -- inflammation of the brain, usually mild, but sometimes severe
- bleeding disorders -- rare but can be fatal
- death -- in rare cases
- shingles can occur in people who have previously had chickenpox.
Reasons for chickenpox immunisation
Immunisation can prevent serious medical complications. For children who have not had chickenpox, the vaccine can help protect them against serious complications associated with chickenpox and protect them from developing shingles later in life.
Immunised children who get chickenpox (this is known as breakthrough chickenpox) generally have a much milder form of the disease. They have fewer skin lesions, a lower fever and recover more quickly.
Research shows that two doses of chickenpox vaccine in children provides increased protection and reduces the risk of chickenpox occurring at a later time. The government funds one free dose of a chickenpox-containing vaccine and a parent can purchase a second dose, on prescription.
Immunisation against chickenpox is provided free of charge to children under the National Immunisation Program Schedule. The dose is a combined vaccine containing protection against measles, mumps, rubella and varicella (MMRV) given at 18 months of age.
In Victoria, immunisation against chickenpox is free for:
- children at 18 months -- immunisation against chickenpox is given as the combination MMRV vaccine. Children who have had chickenpox should still receive the combination vaccine
- young people up to and including 19 years -- free catch-up vaccines are available for all young people who have not been fully immunised.
Adults who do not know if they have had chickenpox disease can have a blood test to check their immunity. If they are not immune, they can purchase the chickenpox vaccine with a prescription.
People from 14 years of age and over are recommended to be immunised with two doses of the chickenpox vaccine, one to two months apart.
Both the combination MMRV vaccine and the chickenpox vaccine contain a very weakened form of chickenpox virus that works by causing the body to produce its own antibodies to protect against the virus.
People who should be immunised against chickenpox
People who benefit most from immunisation include:
- adults not immune to chickenpox (those who have not been immunised and have not had chickenpox), especially parents with young children and people in 'at-risk' occupations such as teachers, childcare workers and healthcare workers
- adults and young children who are not immune (those who have not been immunised and have not had chickenpox), and who live with people with weakened immune systems and no history of chickenpox.
Pregnancy and chickenpox immunisation
If you are thinking of becoming pregnant or you are early in your pregnancy, your healthcare professional can check your immunity with a blood test. If you are not immune and not pregnant, you may decide to receive the chickenpox vaccine before you become pregnant. The MMRV vaccine is not recommended for people 14 years and over.
If you are not immune during your pregnancy, avoid contact with people who have known cases of chickenpox. Contact your doctor, midwife or hospital as soon as possible if you are exposed to anyone with chickenpox.
Before receiving the vaccine, tell your doctor or nurse if you (or your child):
- are unwell (have a temperature over 38.5 ˚C)
- have allergies to any other medicines or substances
- have had a serious reaction to any vaccine
- have had a serious reaction to any component of the vaccine
- have had a severe allergy to anything
- have a disease or you are having treatment that causes low immunity
- have received another vaccine within the last month or if you will have another vaccine within one month of the chickenpox immunisation
- have received a blood or plasma transfusion or immunoglobulins within the last three to 11 months or will need to receive them within three weeks of the chickenpox immunisation
- are taking any prescription or over-the-counter medicines
- are pregnant or intend to become pregnant.
Side effects of chickenpox vaccine
The chickenpox vaccine is effective and safe, but all medications can have unwanted side effects. Side effects from chickenpox vaccine can occur five to 26 days after immunisation and include a mild chickenpox-like rash, usually at the injection site, but occasionally elsewhere on the body.
Other mild side effects occurring in the first few days after immunisation include:
- localised pain, redness and swelling at the injection site
- occasionally, an injection-site lump that may last many weeks (treatment is not needed)
- fever (can be more than 39 ˚C) in the five to 12 days after immunisation.
Managing fever after immunisation
Common side effects following immunisation are usually mild and temporary (occurring in the first few days after vaccination).
Side effects can be reduced by:
- drinking extra fluids and not overdressing if the person has a fever
- although routine use of paracetamol after immunisation is not recommended, if fever is present, paracetamol can be given -- check the label for the correct dose or speak with your pharmacist, (especially when giving paracetamol to children).
Concerns about side effects
If a side effect following immunisation is unexpected, persistent or severe, or if you are worried about yourself or your child's condition after immunisation, see your doctor or immunisation nurse as soon as possible or go directly to a hospital.
It is important to seek medical advice if you (or your child) are unwell, as this may be due to other illness, rather than because of the immunisation.
Immunisation side effects may be reported to the Victorian vaccine safety service
, the central reporting service in Victoria on 1300 882 924, select option one. You can discuss with your immunisation provider how to report adverse events in other states or territories.
Rare side effects
There is a very small risk of a serious allergic reaction (anaphylaxis) to any vaccine. This is why you are advised to stay at the clinic or medical surgery for at least 15 minutes following immunisation in case further treatment is required.
Another rare side effect is thrombocytopenia, which is bleeding caused by insufficient blood platelets.
Immunisation and HALO
The immunisations you may need are decided by your health, age, lifestyle and occupation. Together, these factors are referred to as HALO.
Talk to your doctor or immunisation provider if you think you or someone in your care has health, age, lifestyle or occupation factors that could mean immunisation is necessary. You can check your immunisation HALO using the 'Immunisation for life' infographic.
Where to get help
- In an emergency, always call triple zero (000)
- Emergency department of your nearest hospital
- Your local government immunisation service
- Maternal and child health nurse
- Maternal and Child Health Line (24 hours) Tel. 132 229
- NURSE-ON-CALL Tel. 1300 60 60 24 -- for expert health information and advice (24 hours, 7 days)
- Immunisation Section, Department of Health and Human Services, Victorian Government Tel. 1300 882 008
- Your local pharmacist
- Victorian vaccine safety service Tel.1300 882 924, option one