Varicella-Zoster Vaccine for Chickenpox
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Chickenpox (varicella) is a common contagious illness caused by a type of herpes virus. The chickenpox vaccine (varicella-zoster vaccine) is given by injection.
How It Works
When you receive the chickenpox vaccine, your body reacts by producing antibodies to fight against the varicella virus.
Why It Is Used
Varicella vaccine prevents chickenpox. The vaccine is recommended for all healthy children, teens, and adults who have not had chickenpox. 2, 3
- Babies can receive the vaccine along with some other standard shots (immunizations) that are given between 12 months and 18 months of age. Two doses of this vaccine may be recommended in some provinces.
- Children aged 12 months through 12 years can receive the vaccine at any time.
- Healthy adolescents and young adults aged 13 and older should receive two doses of the vaccine 4 to 8 weeks apart.
- Adults who have not had chickenpox should also receive two doses of vaccine. The vaccine is especially recommended for the following adults:
- People who work in settings where they are likely to come in contact with people with chickenpox (for example, health care workers, child care workers, students in group living situations). Sometimes employers require proof of immunity to or vaccination for chickenpox.
- Non-pregnant women who can have children. Women who have not had chickenpox or the vaccine are at risk for complications of chickenpox during pregnancy.
- Family members of people with impaired immune systems . This protects them from having chickenpox and thus protects their family member who has an impaired immune system.
- People who travel outside Canada and the United States. In some countries (especially tropical countries), chickenpox is a disease of adults.
Older children, teens, and adults can receive the vaccine at any time, but some provinces may test you to see if you’re already immune before you get the vaccine. Some provinces now require proof that children entering daycare and school have either had chickenpox or have been vaccinated to prevent the virus.
People who have been exposed to someone with chickenpox may be able to get the vaccine to prevent or decrease the severity of chickenpox. In these cases, the vaccine should be given within 3 to 5 days after exposure. 1
Chickenpox vaccine is not recommended for:
- Women who are pregnant. Women need to wait 1 month after receiving the chickenpox vaccine before they become pregnant.
- Some people with impaired immune systems.
- People who are taking high doses of corticosteroids by mouth. People who are taking low doses or taking the medications by inhalation (such as people withasthma ) may be able to take the chickenpox vaccine.
- People with serious long-term illnesses, such as children with leukemia .
- People who are allergic to the antibiotic neomycin. The chickenpox vaccine contains a small amount of neomycin.
- People who have recently received immunoglobulin (IG), blood, or plasma. Wait 3 to 11 months after receiving IG, blood, or plasma before you get the chickenpox vaccine.
People who can’t get the vaccine (such as pregnant women and very young children) who have been exposed to someone with chickenpox may get immunoglobulin (IG) to prevent or decrease the severity of chickenpox. Immunoglobulin works best if given within 4 days after exposure. 1 Talk to your doctor if you or your child has been exposed to someone with chickenpox and is at risk of severe complications.
How Well It Works
When you are given the chickenpox vaccine, your body produces antibodies against the chickenpox virus. These antibodies stay in your body and protect you just like they would if you had chickenpox. This is called immunity against chickenpox.
It is not known how long immunity from the vaccine lasts, because the vaccine has only been used in Canada since 1998. So far, people vaccinated against chickenpox since 1998 are still immune. In addition, a chickenpox vaccine given in Japan for more than 20 years still protects people against the virus. 3
Varicella vaccine is safe and effective in preventing chickenpox. 3
- More than 95% of healthy children who receive the vaccine between ages 12 months and 12 years develop immunity to chickenpox.
- Between 78% and 82% of people aged 13 and older who receive one dose of the vaccine are protected against chickenpox; 99% are protected after receiving two doses of the vaccine.
- The vaccine protects against moderate to severe cases of chickenpox in 95% of people immunized and against mild infection in 70% to 85%.
Occasionally chickenpox develops even in people who receive the vaccine. This is called breakthrough infection. However, if this happens, you will likely develop a mild form of the disease, with few blisters and symptoms.
The varicella vaccine has few side effects. The number or severity of side effects does not increase if someone takes the vaccine without knowing whether he or she has had chickenpox. Side effects are usually seen more often in teens and adults than in children.
Side effects of the chickenpox vaccine include:
- Pain, redness, and swelling. About 20% of children have redness or soreness at the injection site. 3
- Rash. About 3% to 5% of children develop a rash around the injection site, and an additional 3% to 5% of children develop a rash all over their body. 3
- Fever. About 10% to 14% of children and 10% of teens and adults have a slight fever [38°C (100°F)] after receiving the vaccine. 4
The fever and rash may not appear until about 2 weeks after the vaccination.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
What To Think About
Consider the following when deciding whether to get the chickenpox vaccine for you or your child.
- Getting the vaccine prevents the spread of chickenpox.
- People who get the chickenpox vaccine are less likely to have shingles later in life than people who have had chickenpox. If vaccinated people do get shingles, symptoms are usually very mild.
- If you are not sure whether you have had chickenpox, you can have a blood test to check for antibodies against the varicella virus. If you have had chickenpox, you will have chickenpox antibodies in your blood and you don’t need the vaccine.
- It is safe for healthy children and adults to get the chickenpox vaccine without knowing whether they have ever had chickenpox. The risk of side effects does not increase if you get the vaccine even though you have had chickenpox in the past.
- Getting the chickenpox vaccine may not prevent chickenpox if you were around someone with chickenpox just before (within 21 days) you received the vaccine. This is because you were infected with the chickenpox virus before you received the vaccine. However, your symptoms may be less severe.
- There is a measles, mumps, rubella, and varicella (MMRV, or Priorix-Tetra) shot that also protects against chickenpox (varicella). Talk to your child’s doctor about the pros and cons of the MMRV shot. It can be given to children age 12 and younger.
- Some parents choose not to give their child the chickenpox vaccine. Not giving your child the vaccine significantly increases his or her chances of having chickenpox at some point, and possibly complications from chickenpox. Talk with your health professional about any questions or concerns you have about giving your child this vaccine.
- Occasionally some people develop a mild rash with a few blisters after having the chickenpox vaccine. If this occurs, you should cover the rash and avoid all people who are at high risk for complications from the chickenpox virus or who have animpaired immune system until the rash is gone and all blisters have dried and crusted over.
- National Advisory Committee on Immunization (NACI) (2006). VariZIG as the varicella zoster immune globulin for the prevention of varicella in at-risk patients. Canada Communicable Disease Report, 32(ACS-8): 1–8. Also available online: http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/06vol32/acs-08/index-eng.php.
- National Advisory Committee on Immunization (NACI) (2006). Canadian Immunization Guide, 7th ed., pp. 1–372. Ottawa: Public Health Agency of Canada. Also available online: http://publications.gc.ca.
- American Academy of Pediatrics (2009). Varicella-zoster infections. In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp. 714–727. Elk Grove Village, IL: American Academy of Pediatrics.
- Chartrand SA (2000). Varicella vaccine. Pediatric Clinics of North America, 47(2): 373–394.
Last Revised: July 22, 2013
Author: Healthwise Staff
Medical Review: John Pope, MD – Pediatrics & Andrew Swan, MD, CCFP, FCFP – Family Medicine & William Atkinson, MD, MPH – Public Health and Preventive Medicine & Thomas Emmett Francoeur, MD, MDCM, CSPQ, FRCPC – Pediatrics