Chickenpox (also called varicella) is a common childhood disease. It is usually mild, but can be serious, especially in young infants and adults. It is not possible to predict who will have a mild case of chickenpox and who will have a serious or even deadly case of the disease. Children with chickenpox miss an average of five-six days of school, and parents or other caregivers miss three-four days of work to care for sick children. Compared with children, adults are at increased risk of complications related to chickenpox.
Vaccination is the best way to prevent infection with varicella—the virus that causes chickenpox. Widespread vaccination also reduces the risk of exposure to infection for persons at risk for serious disease who cannot be vaccinated because of illness or other conditions. The vaccine is safe and effective, and should be used to prevent as many cases as possible.
Who should get chickenpox vaccine and when?
Anyone who is not fully vaccinated, and has never had chickenpox, should receive two doses of chickenpox vaccine. The timing of the doses depends on the person’s age:
Children who have never had chickenpox should get two doses of chickenpox vaccine:
1st Dose: 12-15 months of age
2nd Dose: 4-6 years of age (may be given earlier, if at least 3 months after the 1st dose)
People 13 years of age and older (who have never had chickenpox or received chickenpox vaccine) should get two doses at least 28 days apart.
Chickenpox vaccine may be given at the same time as other vaccines.
How important is it for adults to be vaccinated?
Adolescents and adults are at increased risk for more severe disease from chickenpox. Adults without immunity who might be at increased risk for exposure or transmission should receive special consideration for vaccination. These include:
Health care providers
Household contacts of immune-com- promised persons
Persons who live or work in environments in which chickenpox transmission is likely (e.g., teachers, day-care employees, and residents/staff in institutional settings)
Persons who live or work in places where chickenpox transmission can occur (e.g., college students, inmates and staff of correctional institutions, and military personnel)
Non-pregnant women of childbearing age (women should avoid pregnancy for one month following each vaccine dose)
Adolescents and adults living in households with children
International travellers
Is the vaccine effective in preventing all cases of chickenpox?
No vaccine is 100% effective in preventing disease. For chickenpox vaccine, about 9 out of every 10 people who are vaccinated with two doses are completely protected from chickenpox. In addition, the recommended two-dose regimen is virtually 100% effective in preventing severe disease.
If a vaccinated person does get chickenpox, it is usually a very mild case lasting only a few days and involving fewer skin lesions (usually less than 50, which may resemble bug bites more than typical, fluid-filled chickenpox blisters), mild or no fever, and a quicker recovery.
Is there a blood test available to determine whether or not a person has had chickenpox?
A blood test is available to check immunity, but if it is not available, it is still safe to receive the vaccine even if you have previously had chickenpox.
Is there anyone who should not receive the chickenpox vaccine?
Yes, certain persons should not receive the chickenpox vaccine. These persons are those who:
Have had a serious allergic reaction to any component of the vaccine, including gelatin
Currently have moderate or serious illness (note: vaccine may be given to persons with a mild fever, cold, or diarrhoea)
Are pregnant,
Are unable to fight serious infections because of:
any kind of cancer or cancer treatment with x-rays or drugs (note: if your child has leukaemia in remission and has been off chemotherapy for at least three months, he/she may be eligible to receive the vaccine; ask your doctor)
a disease that depresses cellular immune function (note: if your child has HIV infection but has sufficient immune functioning he/she may receive the vaccine; ask your doctor)
treatment with drugs such as long-term steroids
Have received blood products (such as immune globulin or a blood transfusion) during the past 3-11 months,depending on dosage
Have a family history of congenital hereditary immunodeficiency, unless they are known to be immunocompetent.
The vaccine manufacturer also recommends that persons receiving the chickenpox vaccine avoid using salicylates (aspirin products) for six weeks after receiving vaccination because of the association between aspirin use and Reye syndrome following chickenpox.
What problems can occur after taking the chickenpox vaccination?
Soreness, redness, or swelling where the injection was given is the most common side effect
About 1%-4% of vaccine recipients develop a mild rash or several small bumps following chickenpox vaccination. (In very rare instances, it may be possible for someone who gets a rash from the chickenpox vaccine to transmit vaccine virus chickenpox to another person. Persons developing a rash after vaccination should take extra precautions to avoid contact with anyone whose immune system is not working properly.
Mild fever two weeks after the vacci- nation.
In rare cases, a seizure (jerking and staring spell) usually caused by fever. This may not be related to the vaccine.
If a woman was recently vaccinated and then found she was pregnant, what should she do?
If she discovered she was pregnant when she got the chickenpox vaccine, or got pregnant within three months after getting the vaccine, she should contact her doctor. There is a theoretical risk that when administered one month prior to or during pregnancy, the vaccine may cause birth defects similar to those that can occur from natural chickenpox.
Can a child vaccinated two-three years ago still develop a mild case of chickenpox?
After vaccination, some persons do not develop enough protection to completely prevent them from developing chickenpox. When they come into close contact with a person with chickenpox, they may develop a mild case of disease.
Children who were vaccinated in their early childhood years may have their first close contact with another child with chickenpox in child care or school settings several years after vaccination. This is why they may come down with mild chickenpox several years after they were vaccinated. This form of chickenpox is also called “breakthrough” disease.
Can a vaccinated person who devel- ops a mild case of chickenpox still spread the disease?
Yes. Vaccinated persons who get this milder form of chickenpox may still spread the disease to others who are not protected. Therefore, these individuals should stay at home until the blisters have formed scabs or if there are no blisters present, until no new spots or bumps are forming.
If a person who has never had chick enpox or the vaccine comes into close contact with someone with chicken pox, could receiving the vaccine prevent this person from getting chicken pox?
For healthy adolescents and adults (persons aged 13 years and older) without evidence of immunity, varicella vaccination within 3-5 days of exposure to rash is beneficial in preventing or modifying chickenpox. Studies have shown that vaccination administered within three days of exposure to rash is greater than or equal to 90% effective in preventing varicella while vaccination within five days of exposure to rash is approximately 70% effective in preventing varicella and 100% effective in modifying severe disease.
If there are chickenpox cases at school is it too late to have a child vaccinated?
No, it is not too late if the child has not had chickenpox or has not had two doses of the vaccine. At any stage of an outbreak, all susceptible children and adults should be vaccinated and those who previously only received 1 dose of the vaccine should receive the second dose.
(The writer, a Consultant Family Physician is Head, Department of Family Medicine, University of Sri Jayewardenepura,Nugegoda and a Member of the Vaccine Forum)
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