ATLANTA Varicella vaccine should be administered to virtually anyone without a reliable history of chickenpox infection, according to recently published guidelines.
Varivax (Merck & Co.) provides 70% to 90% protection against varicella zoster virus (VZV) infection and 95% protection against severe disease seven to 10 years after vaccination.
The recommendations of the Advisory Committee on Immunization Practices (ACIP) call for routine immunization of all children 12 months to 18 months of age; immunization is also recommended for all children younger than 13 years who have not had chickenpox. It may be given at any time during childhood.
Children younger than 13 years receive a single 0.5-mL dose subcutaneously. Varicella vaccine may be administered simultaneously with measles-mumps-rubella vaccine, at a separate site and with separate syringes.
Children 13 years and older and adults receive two 0.5-mL doses, subcutaneously, administered four to eight weeks apart.
Varivax, which is a live vaccine, is not recommended for people with primary or acquired immunodeficiency. Routine screening for HIV infection prior to immunization, however, is not recommended. If a person with HIV infection is inadvertently immunized, the statement suggests using acyclovir to reduce the severity of vaccine-associated disease.
Other contraindications include known allergy to any component of the vaccine, severe illness, pregnancy, or if the person is on steroid or salicylate therapy.
The vaccine is well tolerated in children and adults. The most commonly reported adverse events are mild fever, discomfort at the injection site (e.g., pain, swelling, erythema, rash or induration), varicella-like rash at the injection site or a non-localized rash.
During the first year of use, more than 2.3 million doses have been distributed. Only 24 serious adverse events have been reported: four cases of encephalitis; seven cases of ataxia; 10 cases of erythema multiforme; and three cases of anaphylaxis. A causal relationship between these events and vaccination has not been determined.
Varivax contains no preservatives, so proper handling and storage are crucial to maintaining vaccine potency. The vaccine must be stored frozen at an average temperature of 5° F or colder, and once reconstituted, the product must be used within 30 minutes or discarded.
The guidelines, published in the July 12 issue of Morbidity and Mortality Weekly Report were approved by the ACIP last summer.
For more information:
- CDC. Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices. MMWR 1996;45 (No. RR-11):1-36.
Varicella vaccine is also recommended for susceptible children older than 13 and adults who:
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