Chickenpox Vaccination Service

Chickenpox is caused by a virus, the varicella-zoster virus. 

Chickenpox spreads from person to person by direct contact or through the air by coughing or sneezing. It is highly contagious. It can also be spread through direct contact with the fluid from a blister of a person infected with chickenpox, or from direct contact with a sore from a person with shingles. 

It takes from 10 to 21 days to develop symptoms after being exposed to a person infected with chickenpox.  The usual time period is 14–16 days. 

The most common symptoms of chickenpox are rash, fever, coughing, fussiness, headache, and loss of appetite. The rash usually develops on the scalp and body, and then spreads to the face, arms, and legs. The rash usually forms 200–500 itchy blisters in several successive crops. The illness lasts about 5–10 days.

Many cases of chickenpox are mild, but deaths from this disease can occur. 

Chickenpox also accounts for about 200 hospitalisations each year in Ireland. 

Even children with average cases of chickenpox are uncomfortable and need to be kept out of creche or school for a week or more. 

The most common complication is bacterial infection of the skin or other parts of the body including the bones, lungs, joints, and blood. The virus can also lead to pneumonia or infection of the brain. These complications are rare but serious. Complications are more common in infants, adults, and people with weakened immune systems. 

Usually, chickenpox can be diagnosed by disease history and appearance alone. Adults who need to know if they’ve had chickenpox in the past can have this determined by a laboratory test. 

Patients with chickenpox are contagious for 1–2 days before the rash appears and continue to be contagious through the first 4–5 days or until all the blisters are crusted over.

Most cases of chickenpox in otherwise healthy children are treated with bed rest, fluids, and control of fever. 

Children with chickenpox should NOT receive the following medication: 

• aspirin because of possible subsequent risk of Reye’s syndrome
• ibuprofen can increase the risk of serious skin infections

Paracetamol may be given for fever control. 

Chickenpox may be treated with an antiviral drug in serious cases, depending on the patient’s age and health, the extent of the infection, and the timing of the treatment. 

Both chickenpox and shingles are caused by the same virus. 

After a person has had chickenpox, the virus remains in the body permanently, but silently. About one-third of all people who have been infected with chickenpox later develop the disease known as herpes zoster, or shingles. Symptoms of shingles are pain, itching, blisters, and loss of feeling along a nerve. Most cases occur in people older than 50, and the risk of developing shingles increases with age. 

In Ireland the chickenpox vaccine is not currently part of the routine childhood schedule. It is recommended for those in close contact with people who are particularly at risk of complications from chickenpox. This includes: 

• Healthcare workers of all kinds who are not immune to chickenpox
• Healthy family members and contacts of people without a fully working immune system (for example, those with HIV, those without a spleen, people who have had an organ transplant, and those receiving chemotherapy treatment). As the chickenpox vaccine is a live vaccine, people without a fully working immune system cannot receive the vaccine themselves.

In Ireland the vaccine is given to adults and children over the age of one year. Two doses are given, at least 4 weeks apart. The exact spacing between doses depends on the age of the person receiving the vaccine. 

The chickenpox vaccine should not be given to people who are clinically immunosuppressed (either due to drug treatment or underlying illness). This is because the vaccine strain could replicate too much and cause a serious infection. This includes babies whose mothers have had immunosuppressive treatment while they were pregnant or breastfeeding. 

The chickenpox vaccine is not recommended for pregnant women as a matter of caution. However, studies have not shown any link between the weakened virus in the vaccine and any specific problems in babies born to women who received a chickenpox vaccine while they were pregnant. See 'Is the vaccine safe?' below

Two doses of the vaccine give about 98% protection in children and about 75% protection in teenagers and adults. 

For full information on side effects, ask for the Patient Information leaflet for the vaccine you are offered. As a general guide, side effects may be experienced as listed below. 

Very common (affecting more than 1 in 10 people at each dose): 

• reactions at the site of the injection, including redness, pain and swelling.
• raised temperature (fever)

Common (affecting up to 1 in 10 people at each dose): 

• chickenpox-like rash (in up to 10% of adults and 5% of children)
• mild cold-like symptoms
• irritability
• itching at the injection site

Uncommon (affecting up to 1 in 100 people at each dose): 

• swollen glands, headache, sore throat, cough, or runny nose
• feeling sick or being sick
• diarrhoea
• a rash with blisters
• joint or muscle pain
• very high temperature
• drowsiness, tiredness, or feeling generally unwell

Because the chickenpox vaccine is live, there is a very small risk that someone who has been vaccinated could pass on the virus to someone who is not immune to chickenpox. This is usually only a risk if the person who has been vaccinated develops a chickenpox type rash at the injection site or elsewhere on the body. 

The chickenpox vaccine should not be given to people who are clinically immunosuppressed (either due to drug treatment or underlying illness). This is because the vaccine strain could replicate too much and cause a serious infection. This includes babies whose mothers have had immunosuppressive treatment while they were pregnant or breastfeeding. 

The chickenpox vaccine is not recommended for pregnant women as a matter of caution. Women who have had the vaccine are advised to avoid getting pregnant for one month after vaccination. However, studies have been carried out on pregnant women who have accidentally received chickenpox vaccine before they knew they were pregnant. These have not shown any link between the weakened virus in the vaccine and any specific problems in babies born to these women.