Chickenpox

About chickenpox

Chickenpox (also known as varicella) is a highly infectious viral infection caused by the varicella-zoster virus.

It usually causes mild illness but can reappear later in life as shingles. Newborn babies, pregnant women and people with a weakened immune system are at increased risk of serious illness.

Anyone who has not had chickenpox or who has not been vaccinated against chickenpox is at risk of infection.

Symptoms of chickenpox

Symptoms of chickenpox can occur within 2 to 3 weeks after exposure to the virus.

Symptoms can include:

• low-grade fever
• headache
• runny nose
• sore throat
• feeling generally unwell
• skin rash.

The rash usually begins with small lumps that turn into blisters, which burst and eventually scab over after about 5 days. The rash can affect the body, limbs and head, including the mouth, eyelids or genital area. The rash is usually itchy and can potentially lead to scarring.

Most people with chickenpox have a mild, self-limiting illness, especially people who have been vaccinated against chickenpox. Chickenpox tends to be more severe in adults than children.

Some people can have serious illness with complications such as:

• cellulitis – infection and inflammation of the skin
• pneumonia – infection and inflammation of the lungs
• hepatitis – inflammation of the liver
• encephalitis – inflammation of the brain
• very rarely, chickenpox can be fatal.

People who have previously had chickenpox can develop shingles later in life.

Chickenpox and shingles

For some infected people, the varicella-zoster virus that causes chickenpox can reappear later in life to cause shingles. After causing chickenpox, the virus becomes inactive in the nerve cells of the body. When it reactivates it can cause shingles.

Symptoms of shingles include a painful rash that blisters. Anti-viral medication and pain medication may be required to treat shingles.

One in 3 adults who have had chickenpox will develop shingles in their lifetime. The incidence and severity of shingles increases with age.

People with shingles should avoid contact with others, especially people at increased risk of serious illness from chickenpox. People who do not have immunity against chickenpox can become infected with chickenpox (not shingles) if they come into contact with the fluid in the blisters of a person with shingles.

How chickenpox spreads

Chickenpox is spread from person-to-person by:

• breathing in very small droplets that contain the virus which is breathed out by an infected person, such as from coughing or sneezing
• touching the fluid in the blisters of an infected person. Blisters that have scabbed do not spread infection.

People with chickenpox are infectious from 2 days before the onset of the rash until all the blisters have scabbed.

Chickenpox in pregnancy

Most pregnant women have immunity against chickenpox. However, some pregnant women can become infected and have serious illness. Complications include pneumonia, hepatitis and encephalitis.

Chickenpox in pregnant women can lead to birth abnormalities in the baby. These include abnormalities of the skin, arms and legs, eyes, brain and potentially other parts of the body. The risk is highest during the first 20 weeks of pregnancy.

There is also the risk of the newborn baby developing chickenpox and other complications.

If you are planning a pregnancy you should speak to your doctor to review your vaccination status and check your immunity with a blood test.

If you do not have immunity against chickenpox you are recommended to take precautions:

• If you are not pregnant, you should be vaccinated before becoming pregnant. Two doses of chickenpox vaccine are recommended and should be given at least 4 weeks apart.
• If you are pregnant and not immune you should avoid contact with people with chickenpox. Pregnant women cannot receive the chickenpox vaccine. If you are exposed to chickenpox, contact your doctor, midwife or hospital as soon as possible, as an injection of varicella-zoster immunoglobulin (VZIG) may be recommended.

Diagnosis of chickenpox

Chickenpox is usually diagnosed by your doctor, with laboratory testing of a sample of the blister fluid to help confirm the diagnosis.

A blood test can also be done to check for immunity against chickenpox.

Treatment of chickenpox

For most people, chickenpox causes mild illness that gets better without specific treatment. You can relieve symptoms and prevent complications by:

• resting
• drinking plenty of fluids to prevent dehydration
• using paracetamol to bring down fevers
• using creams or lotions, such as calamine lotion, to reduce the itching – if you have a skin condition such as eczema ask your doctor or pharmacist about other available creams
• wearing mittens to prevent scratching – these can be worn by babies and young children
• having colloidal oatmeal baths may also help reduce itching.

People with serious illness may need treatment with antiviral medication and hospital admission.

Prevention of chickenpox

People with chickenpox should avoid contact with other people, particularly those at increased risk of serious illness, such as newborn babies, pregnant women and people with a weakened immune system.

Children with chickenpox must not go to school, kindergarten or childcare until all blisters have scabbed. Parents, guardians or carers should inform the school, kindergarten or childcare centre as testing and treatment may be recommended for workers and other children.

Chickenpox can be prevented through vaccination. Two doses of vaccine (varicella-containing vaccine) are recommended. Vaccination helps protect against infection and serious illness.

Chickenpox vaccination for children under 14 years of age

In Australia, all children under 14 years of age are recommended to receive 2 doses of a varicella-containing vaccine.

• The first dose is available free of charge under the National Immunisation Program Schedule (NIP). It is given at 18 months of age as part of the combination MMRV (measles, mumps, rubella and varicella) vaccine. The MMRV vaccine can be given safely in children who have already had chickenpox infection prior to 18 months of age.
• The second dose is available by private prescription. Parents, guardians or carers can arrange the second dose through their doctor or immunisation provider. The second dose should be given at least 4 weeks after the first dose.

Immunised children who get chickenpox (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.

Chickenpox vaccination for adolescents aged 14 years and over and adults

Adolescents aged 14 years and over and adults are recommended to receive 2 doses of vaccine. The 2 doses should be given at least 4 weeks apart. The combination MMRV vaccine is not recommended for people aged 14 years and over.

People who have previously been infected with chickenpox or who have blood tests showing evidence of immunity may not require vaccination.

Free catch-up vaccination is available under the NIP for all eligible people under the age of 20 years, and refugees, asylum seekers and humanitarian entrants of any age. The first dose is funded under the NIP for eligible people. Other non-immune people aged 20 years and over require a private prescription.

Chickenpox vaccination for specified occupations

People who work in healthcare, childhood education and childcare, or long term-care facilities are strongly recommended to have 2 doses of chickenpox vaccine if they are not immune.

For further information, see your doctor or immunisation provider.

How we can protect our community from chickenpox

High levels of vaccination in the community can prevent the spread of chickenpox and protect people in the community who cannot be vaccinated, such as those who are too young or too unwell. This is called herd immunity.

Children with chickenpox must not go to school, kindergarten or childcare centres until all blisters have dried.

You can look after your own family and protect vulnerable people in your community by:

• ensuring you and your family are fully vaccinated
• keeping children with chickenpox home from school, kindergarten or childcare until all blisters have scabbed.
• if you or a family member has chickenpox or shingles, avoiding contact with other people, particularly those at increased risk of serious illness, such as newborn babies, pregnant women and people with a weakened immune system.

While the number of chickenpox infections have decreased with widespread vaccination through the NIP, chickenpox is highly infectious.

In Victoria, chickenpox is a notifiable condition that is reported by doctors to the Department of Health.

People who are exposed to chickenpox and are not immune may be given treatment to reduce their risk of infection and serious illness through:

• vaccination within 5 days of exposure
• an injection of varicella-zoster immunoglobulin (VZIG) for people with an increased risk of serious illness, usually within 4 days (96 hours) of exposure, but can be given as late as 10 days after exposure.

Where to get help

• In an emergency, always call triple zero (000)
• Emergency department of your nearest hospital
• Your GP (doctor)
• Local government immunisation service – visit Know Your Council
• Local Public Health Unit
• Maternal and Child Health Line (24 hours, 7 days) Tel. 13 22 29
• NURSE-ON-CALL Tel. 1300 60 60 24 – for expert health information and advice (24 hours, 7 days)
• Immunisation Unit, Department of Health, Victorian Government Email: immunisation@health.vic.gov.au
• Pharmacist