February 27, 2015
There are two types of varicella vaccines:
- A chickenpox vaccine for vaccinating children, adolescents, and adults
- A shingles vaccine for vaccinating adults age 60 years and older
The live-virus varicella vaccine (Varivax) produces persistent immunity against chickenpox. The vaccine can prevent chickenpox or reduce the severity of the illness if it is used within 3 days, and possibly up to 5 days, after exposure to the infection.
The childhood chickenpox vaccine can also be given as part of a combination vaccine (Proquad) that combines measles, mumps, rubella (together called MMR), and varicella in one product. However, recent data indicate that combining varicella and MMR vaccinations into one shot doubles the risk for febrile (fever-related) seizures in children ages 12 - 24 months compared to giving separate MMR and varicella injections. Parents should consider the lower risk associated with separate injections.
Recommendations for the Chickenpox Vaccine in Children
The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) recommends that children receive TWO doses of the chickenpox vaccine with:
- The first dose administered when the child is 12 - 15 months years of age, and
- The second dose administered when the child is 4 - 6 years of age
For children who have previously received one dose of the chickenpox vaccine, the ACIP recommends that they receive a “catch-up” second dose during their regular doctor’s visit. This second dose can be given at any time as long as it is at least 3 months after the first dose. Doctors pushed for the new second-dose policy due to a number of recent chickenpox outbreaks among previously vaccinated schoolchildren.
Children most at risk for having chickenpox after having been vaccinated only one time are ages 8 - 12 years and have generally been vaccinated at least 5 years before their current chickenpox infection.
Recommendations for the Chickenpox Vaccine in Adults
The U.S. Centers for Disease Control and Prevention (CDC) recommends that every healthy adult without a known history of chickenpox be vaccinated. Adults should receive 2 doses of the vaccine, 4 - 8 weeks apart. Adults in the following groups should especially consider vaccination:
- Those with high risk of exposure or transmission (hospital or day care workers, parents of young children)
- People who may come in contact with those who have compromised immune systems
- Nonpregnant women of childbearing age
- International travelers
As with other live-virus vaccines, the chickenpox vaccine is not recommended for:
- Women who are pregnant or who may become pregnant within 30 days of vaccination. . (Women who are pregnant and not immunized should receive the first dose of the vaccine upon completion of their pregnancy.)
- People whose immune systems are compromised by disease or drugs (such as after organ transplantation).
Patients who cannot be vaccinated but who are exposed to chickenpox receive immune globulin antibodies against varicella virus. This helps prevent complications of the disease if they become infected.
Side Effects of the Varicella (Chickenpox) Vaccine
- Discomfort at the Injection Site. Fewer than 80% of vaccine recipients have pain, swelling, or redness at the injection site.
- Severe Side Effects. Only about 5% of adverse reactions are serious. These reactions include seizures, pneumonia, anaphylactic reaction, encephalitis, Stevens-Johnsons syndrome, neuropathy, herpes zoster, and blood abnormalities.
- Risk of Transmission. The vaccine may produce a mild rash within about a month of the vaccination, which can transmit chickenpox to others. Individuals who have recently been vaccinated should avoid close contact with anyone who might be susceptible to severe complications from chickenpox until the risk for a rash passes.
- Later Infection. Months or even years after the vaccination, some people develop a mild infection called modified varicella-like syndrome (MVLS). The condition appears to be less contagious and has fewer complications than naturally acquired chickenpox.
In 2006, a shingles vaccine was approved for use in the United States. The zoster vaccine (Zostavax) is a stronger version of the chickenpox vaccine. Study results suggest that the zoster vaccine can prevent about half of all shingles cases and two-thirds of postherpetic neuralgia cases. The CDC recommends that all adults age 60 years and older who have intact immune systems should receive this vaccine. . The vaccine does not appear to not work well in patients age 80 years and older and is generally not recommended for this age group.
Varicella-Zoster Immune Globulin
Varicella-zoster immune globulin (VariZIG) is a substance that mimics the normal immune response against the varicella-zoster virus. It is used to protect high-risk patients who are exposed to chickenpox. Such groups include:
- Pregnant women with no history of chickenpox who have not been previously immunized
- Newborn infants whose mothers had signs or symptoms of chickenpox around the time of delivery (5 days before to 2 days after)
- Premature infants
- Immunocompromised children and adults with no antibodies to VZV
- Recipients of bone-marrow transplants (even if they have had chickenpox)
- Patients with a debilitating disease (even if they have had chickenpox)
For these patients, VariZIG should be given within 96 hours of exposure to someone with chickenpox. (Note: VariZIG is a new formulation of an older drug called VZIG, which is no longer being produced.)
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