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Prevention of Varicella: Recommendations of the U.S. Advisory Committee on Immunization Practices

August 13, 2007

Summary of Recommendations for Varicella Vaccination

Routine Childhood Schedule

· Routine childhood vaccination should be 2 doses.
· Preschool-aged children should receive the first dose of varicella vaccine at age 12-15 months.
· School-aged children should receive the second dose at age 4-6 years (may be administered earlier provided >=3 months have elapsed after the first dose)

Persons Aged >=13 Years

· Persons aged >=13 years should receive 2 doses of vaccine, doses (4-8 weeks apart).
· All adolescents and adults without evidence of immunity should be vaccinated.
· Because of their increased risk for transmission to persons at high risk for severe disease or their increased risk of exposure, vaccination is especially important for persons without evidence of immunity in the following groups:
· Persons who have close contact with persons at high risk for serious complications (e.g., health-care personnel and household contacts of immunocompromised persons)
· Persons who live or work in environments in which transmission of varicella zoster virus is likely (e.g., teachers, child-care workers, and residents and staff in institutional settings)
· Persons who live and work in environments in which transmission has been reported (e.g., college students, inmates and staff members of correctional institutions, military personnel)
· Nonpregnant women of childbearing age
· Adolescents and adults living in households with children
· International travelers

Prenatal Assessment and Postpartum Vaccination

Prenatal assessment of women for evidence of varicella immunity is recommended. Upon completion or termination of pregnancy, women who do not have evidence of varicella immunity should be vaccinated.

Vaccination of Human Immunodeficiency Virus (HIV)-Infected Persons

Vaccination should be considered for HIV-infected children with age-specific CD4+ T-lymphocyte percentage >=15% and may be considered for adolescents and adults with CD4+ T-lymphocyte count >=200 cells/microL.

Outbreak Control

· 2-dose vaccination policy

Postexposure Prophylaxis

· Recommended within 3-5 days

Requirements for Entry to Child Care, School, College, and Other Postsecondary Educational Institutions

All states should require that students at all grade levels (including college) and those in child care centers receive varicella vaccine unless they have other evidence of immunity of varicella.

Evidence of Immunity to Varicella

Evidence of immunity to varicella includes any of the following:

· Documentation of age-appropriate vaccination with a varicella vaccine:


Preschool-aged children (i.e., aged >=12 months): 1 dose

School-aged children, adolescents, and adults: 2 doses¹


· Laboratory evidence of immunity² or laboratory confirmation of disease
· Birth in the United States before 1980³
· Diagnosis or verification of a history of varicella disease by a health-care provider⁴
· Diagnosis or verification of a history of herpes zoster by a health-care provider.

¹ For children who received their first dose at age <13 years and for whom the interval between the 2 doses was >=28 days, the second dose is considered valid.

² Commercial assays can be used to assess disease-induced immunity, but they lack sensitivity to always detect vaccine-induced immunity (i.e., they might yield false-negative results).

³ For health-care personnel, pregnant women, and immunocompromised persons, birth before 1980 should not be considered evidence of immunity.

⁴ Verification of history or diagnosis of typical disease can be provided by any health-care provider (e.g., school or occupational clinic nurse, nurse practitioner, physician assistant, or physician). For persons reporting a history of, or reporting with, atypical or mild cases, assessment by a physician or their designee is recommended, and one of the following should be sought: 1) an epidemiologic link to a typical varicella case or to a laboratory-confirmed case or 2) evidence of laboratory confirmation if it was performed at the time of acute disease. When such documentation is lacking, persons should not be considered as having a valid history of disease because other diseases might mimic mild atypical varicella.

Use of Varicella Zoster Immune Globulin (VZIG) for Postexposure Prophylaxis

· VZIG provides maximum benefit when administered as soon as possible after exposure, but it might be effective if administered as late as 96 hours after exposure.
· The recommended dose of VZIG is 125 U/10 kg body weight, up to a maximum of 625 U. The minimum dose is 125 U.
· The decision to administer VZIG should be based on three factors: 1) whether the patient lacks evidence of immunity, 2) whether the exposure is likely to result in infection, and 3) whether the patient is at greater risk for complications than the general population.

The following patient groups are at risk for severe disease and complications from varicella and should receive VZIG (refer to the original guideline document for additional details):

· Immunocompromised patients. VZIG is used primarily for passive immunization of immunocompromised persons without evidence of immunity after direct exposure to varicella or disseminated herpes zoster (HZ) patients, including persons who 1) have primary and acquired immune-deficiency disorders, 2) have neoplastic diseases, and 3) are receiving immunosuppressive treatment.
· Neonates whose mothers have signs and symptoms of varicella around the time of delivery. VZIG is indicated for neonates whose mothers have signs and symptoms of varicella within 5 days before and 2 days after delivery.
· Premature neonates exposed postnatally. Premature infants who have substantial postnatal exposure should be evaluated on an individual basis. The risk for complications of postnatally acquired varicella in premature infants is unknown. However, because the immune system of premature infants is not fully developed, administration of VZIG to premature infants born at >=28 weeks of gestation who are exposed during the neonatal period and whose mothers do not have evidence of immunity is indicated. Premature infants born at <28 weeks of gestation or who weigh >=1000 g at birth and were exposed during the neonatal period should receive VZIG regardless of maternal immunity, because such infants may not have acquired maternal antibody. The majority of premature infants born at >=28 weeks of gestation to immune mothers have enough acquired maternal antibody to protect them from severe disease and complications.
· Pregnant women. VZIG should be strongly considered for pregnant women without evidence of immunity who have been exposed. Neonates born to mothers who have signs and symptoms of varicella within 5 days before to 2 days after delivery should receive VZIG regardless of whether the mother received VZIG.

Interval Between Administration of VZIG and Varicella Vaccine

Any patient who receives VZIG to prevent varicella should receive varicella vaccine subsequently, provided the vaccine is not contraindicated. Varicella vaccination should be delayed until 5 months after VZIG administration. Varicella vaccine is not needed if the patient has varicella after administration of VZIG.

Antiviral Therapy

Because VZIG might prolong the incubation period by >=1 week, any patient who receives VZIG should be observed closely for signs or symptoms of varicella for 28 days after exposure. Antiviral therapy should be instituted immediately if signs or symptoms of varicella disease occur. The route and duration of antiviral therapy should be determined by specific host factors, extent of infection, and initial response to therapy.

BIBLIOGRAPHIC SOURCE(S)

· Marin M, Guris D, Chaves SS, Schmid S, Seward JF, Advisory Committee on Immunization Practices, Centers for Disease Control. Prevention of varicella: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 2007 Jun 22;56(RR-4):1-40. [204 references] PubMed

This guideline updates a previous version: Prevention of varicella. Updated recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR Recomm Rep 1999 May 28;48(RR-6):1-5.


SOURCE: National Guideline Clearinghouse

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