Varicella fact sheet

What is varicella?
Varicella, commonly known as chickenpox, is an illness caused by a virus, known as the varicella-zoster virus. The illness is usually mild and of short duration with complete recovery in otherwise healthy children, but can be more serious in older age and in immunocompromised individuals. The same virus remains in nerve ganglia and can later reactivate to cause shingles (see below).

Who gets chickenpox?
The disease occurs worldwide. Most people get chickenpox when they are young. In temperate climates more than 90% of chickenpox cases occur before adolescence with the highest incidence in children aged 1-9 years.

What are the symptoms of chickenpox?
Symptoms start 10 to 21 days after exposure to the virus and include fever, tiredness, and an itchy rash with small blisters that dry up and form scabs within 1 to 2 days. The rash is more concentrated over the trunk, face and scalp, and different stages can occur at any one time. These lesions are superficial and the scabs fall off after 1-2 weeks, frequently leaving spots of hypopigmentation that can remain for several months or leave persistent scars.

What are the complications associated with chickenpox?
Chickenpox is usually a mild to moderate disease. Children with serious medical conditions are at greater risk to develop severe complicated chickenpox and may even die from chickenpox pneumonia or encephalitis (an inflammation of the brain). Adults are often more severely affected than children and can develop pneumonia or encephalitis. If a pregnant woman develops chickenpox in pregnancy there is a small but real chance of damage to her unborn baby. In addition, chickenpox may be more severe in pregnant women than in others.

What is shingles?
Some people who have had chickenpox may develop shingles later in life. Shingles, or herpes zoster, occurs when the chickenpox virus lying dormant in the nerve ganglia becomes reactivated years or decades later. Shingles is a painful localised blistering rash often with a burning sensation, tingling, or extreme sensitivity to the skin. In some people, the area where the rash was located becomes extremely painful after the rash has gone and can last from a few weeks to several months.

How is chickenpox spread?
Chickenpox is a very contagious illness and most epidemics occur in winter and early spring, presumably because of greater person-to-person contact at the time. Because the chickenpox virus is found in the secretions in a person's nose and mouth, the virus is spread through coughs and sneezes and through direct contact with the fluid in the blisters of the rash. The dry scabs are not infectious. The disease remains contagious from a day or two before the rash appears until all the blisters form scabs. Since shingles blisters also contain the virus, a person who has never had chickenpox can become infected with chickenpox from someone who has shingles.

What can be done to prevent the spread of chickenpox?
Persons with chickenpox should stay away from others until the blisters are dry and crusted. Therefore they should not attend school or child care facilities until the blisters are dry and crusted.
A varicella vaccine is available to prevent the disease. The suggested vaccination schedule is one dose for children up to 12 years, and two doses, 4-8 weeks apart for people 13 years or older.
Premature infants, immunocompromised persons, or pregnant women may need a shot of VZIG (varicella-zoster immune globulin) to prevent chickenpox after exposure. Persons of any age who have never had chickenpox should receive varicella vaccine within 3 to 5 days of exposure to reduce the risk of developing chickenpox .

Is the chickenpox vaccine safe?
The chickenpox vaccine is safe and effective. The vaccine is approximately 80-85 percent effective in preventing disease. The most common side effect is soreness at the site of injection. Severe side effects are rare. Most people who get vaccinated will not get chickenpox; and if they do get chickenpox, it is usually very mild.

Does past infection with chickenpox make a person immune?
One episode of chickenpox almost always gives life-long protection against further episodes of chickenpox, but years later may be followed by an episode of shingles (see above).

Are there any plans to eliminate chickenpox?
Unlike the case for measles, rubella and congenital rubella syndrome there are no plans to eliminate chickenpox in Europe . However, in some countries chickenpox vaccination is recommended for children. In Europe chickenpox vaccination is part of the routine childhood immunisation in Germany and Italy.

Note: The information presented by this fact sheet is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals.