Chickenpox is a very common illness. It is caused by a virus and most people catch it during their childhood. If you haven’t had chickenpox as a child you can still get it as an adult. Chickenpox is also referred to as varicella, which is the name of the virus that causes it.

Although it’s not usually dangerous, chickenpox can be very unpleasant as it causes an itchy rash and a fever. In most cases, the symptoms clear within a week.

The virus can be dangerous for patients with an impaired immune system, newborn babies and pregnant women.

Once you have had chickenpox, you’re usually immune for life but you could develop shingles at a later point in life.

Chickenpox is caused by the varicella-zoster virus. You catch it by coming into contact with someone who is infected.

Chickenpox is a very contagious infection. Around 90% of people who have not previously had chickenpox will become infected when they come into contact with the virus.

The chickenpox virus is spread most easily from someone who has the rash. The blisters are very itchy and break open easily, which can contaminate surfaces or objects. The virus may then be transferred by touching the surface or object, then touching your face.

The virus is also contained in the millions of tiny droplets that come out of the nose and mouth when an infected person coughs or sneezes. This can also contaminate surfaces or objects.

It normally takes 14 days for the symptoms of chickenpox to show after you have come into contact with the virus. However, this can vary from person to person – from as little as 7 days, up to 21 days. This is called the “incubation period”.

Someone with chickenpox is most infectious from 1 to 2 days before the rash appears, until all the blisters have crusted over. This usually takes 5 to 6 days from the start of the rash.

If you have not had chickenpox before, you can also catch chickenpox from someone with shingles (an infection caused by the same virus). However, it’s not possible to catch shingles from someone who has chickenpox.

Chickenpox is highly contagious. You’re most infectious one to two days before your rash appears, so you can spread it to other people before you even realise you have it. You remain infectious until all your spots crust over (usually about five days after the rash appears).

You’re no longer infectious when all your spots have crusted over. This is usually around five days after the chickenpox rash appears. But, if you’ve had chickenpox, the varicella zoster virus will stay in your body for the rest of your life.

An itchy, spotty rash is the main symptom of chickenpox. It can be anywhere on the body.

Chickenpox happens in 3 stages. But new spots can appear while others are becoming blisters or forming a scab.

Stage 1: small spots appear

The spots can:

• be anywhere on the body, including inside the mouth and around the genitals, which can be painful
• spread or stay in a small area
• be red, pink, darker or the same colour as surrounding skin, depending on your skin tone
• be harder to see on brown and black skin

Stage 2: the spots become blisters

The spots fill with fluid and become blisters. The blisters are very itchy and may burst.

Stage 3: the blisters become scabs

The spots form a scab. Some scabs are flaky while others leak fluid.

Other symptoms

Before or after the rash appears, you might also get:

• a high temperature
• aches and pains, and generally feeling unwell
• loss of appetite

Chickenpox is very itchy and can make children feel miserable, even if they do not have many spots.

The chickenpox spots look the same on children and adults. But adults usually have a high temperature for longer and more spots than children.

It’s possible to get chickenpox more than once, but it’s unusual.

Complications from chickenpox can occur, but they are not common in healthy people who get the disease.

People who may get a serious case of chickenpox and may be at high risk for complications include:

• Infants
• Adolescents
• Adults
• People who are pregnant
• People with bodies that have a lowered ability to fight germs and sickness (weakened immune systems) because of illness or medications, for example,
• People with HIV/AIDS or cancer
• Patients who have had transplants, and
• People on chemotherapy, immunosuppressive medications, or long-term use of steroids.

Serious complications from chickenpox include:

• Bacterial infections of the skin and soft tissues in children, including Group A streptococcal infections
• Infection of the lungs (pneumonia)
• Infection or swelling of the brain (encephalitis, cerebellar ataxia)
• Bleeding problems (hemorrhagic complications)
• Bloodstream infections (sepsis)
• Dehydration

Some people with serious complications from chickenpox can become so sick that they need to be hospitalized. Chickenpox can also cause death.

Deaths are very rare now due to the vaccine program. However, some deaths from chickenpox continue to occur in healthy, unvaccinated children and adults. In the past, many of the healthy adults who died from chickenpox contracted the disease from their unvaccinated children.

Chickenpox can sometimes be spread through contact with objects that have been contaminated with the virus, such as children’s toys, bedding or clothing.

If someone in your household has chickenpox, you can help stop the virus spreading by wiping any objects or surfaces with a sterilising solution and making sure that any infected clothing or bedding is washed regularly.

The flu vaccine does not interfere with the chickenpox vaccine so you can have these at the same time or at any time interval.

If you find out you’re pregnant within a month of having the chickenpox vaccine, it’s best to contact your GP for advice.

Do not worry. A study in the US of nearly 700 women who’d received the chickenpox vaccine while pregnant found no cases of babies affected by the vaccine.

If you or your child have chickenpox, you may not be allowed to fly until 6 days after the last spot has appeared.

You and your child should be safe to fly once you’re past the infectious stage and all of the blisters have crusted over. However, it’s best to check the policy of your airline first. Inform the airline as soon as chickenpox is diagnosed.

It is also important to let your travel insurer know if you or your child has chickenpox. You need to make sure that you’ll be covered if you have to delay or cancel your holiday, or if you need to extend your stay until your child is well enough to fly home.

If your child has already had chickenpox, they are considered to have lifelong immunity, so there is no need for them to be vaccinated.

However, if it is unclear whether or not your child has had chickenpox, they can still be vaccinated as this can prevent future disease and it is unlikely to cause any harm even if they have had chickenpox before.

Chickenpox is transmitted directly by close contact or droplet spread and it can take several days for symptoms to develop. If you believe your child has been exposed to chickenpox and is not showing any symptoms, they may still have the vaccine. Vaccination within 3 days of exposure may help prevent chickenpox or reduce the severity of disease, resulting in fewer skin lesions and a shorter period of illness. However, there is limited information that being vaccinated up to 5 days after exposure may reduce disease severity.

Firstly you’ll need to stay away from school, nursery or work until all the spots have formed a scab. This is usually 5 days after the spots appeared.

Do

•   drink plenty of fluid (try ice lollies if your child is not drinking) to avoid dehydration
•   take paracetamol to help with pain and discomfort
•   cut your child’s fingernails and put socks on their hands at night to stop them scratching
•   use cooling creams or gels from a pharmacy
•   speak to a pharmacist about using antihistamine medicine to help itching
•   bathe in cool water and pat the skin dry (do not rub)
•   dress in loose clothes

Don’t

•   do not use ibuprofen unless advised to do so by a doctor, as it may cause serious skin infections
•   do not give aspirin to children under 16
•   do not go near newborn babies, people who are pregnant and people with a weakened immune system, as chickenpox can         be dangerous for them
•   do not scratch the spots, as scratching can cause scarring

Common side effects

The most common side effects of the chickenpox vaccine are:

• soreness and redness around the site of the injection – this happens in around 1 in 5 children and 1 in 4 teenagers and adults
• a mild rash – this happens in 1 in 10 children and 1 in 20 adults
• high temperature

Serious side effects

Serious side effects of the chickenpox vaccine, such as a serious allergic reaction (anaphylaxis), are rare. They occur in around 1 in a million vaccinated people.

Although the chickenpox vaccine is not part of the routine NHS childhood immunisation schedule in the UK, it is in some other countries, such as the US and Germany.

Millions of doses of the vaccine have been given, and there is no evidence of any increased risk of developing a long-term health condition as a result of the vaccination.

Monitoring safety of vaccines

In the UK, the safety of vaccines is monitored through the Yellow Card Scheme regulated by the Medicines and Healthcare products Regulatory Agency (MHRA) and the Commission on Human Medicines.

Most reactions reported through the Yellow Card Scheme have been minor, such as redness and swelling at the injection site, rashes, fever and vomiting.