Varicella Vaccine Update

Recommendations for routine varicella vaccination were published by the American Academy of Pediatrics in May 1995, but many eligible children remain unimmunized. This update provides additional information on the varicella disease burden before the availability of varicella vaccine, potential barriers to immunization, efforts to increase the level of coverage, new safety data, and new recommendations for use of the varicella vaccine after exposure and in children with human immunodeficiency virus infections. Pediatricians are strongly encouraged to support public health officials in the development and implementation of varicella immunization requirements for child care and school entry. ABBREVIATIONS. AAP, American Academy of Pediatrics; ACIP, Advisory Committee on Immunization Practices; CDC, Centers for Disease Control and Prevention; CI, confidence interval; VZV, varicella-zoster virus; VZIG, varicella-zoster immune globulin. Varicella vaccine (Varivax, Merck and Company, Inc, West Point, PA) was licensed on March 17, 1995, by the US Food and Drug Administration for use in healthy persons 12 months of age or older who have not had varicella. Recommendations for vaccine use were published by the American Academy of Pediatrics (AAP) in May 1995 and by the Advisory Committee on Immunization Practices (ACIP) in July 1996.1,2 Updated recommendations of the ACIP were published in May 1999.3 Despite the recommendations, many eligible children remain unimmunized. Annualized estimates from July 1997 to June 1998 revealed that national varicella vaccine coverage of children 19 to 35 months of age was 34% with wide variations in state and urban areas, ranging from 6% to 52% (Centers for Disease Control and Prevention [CDC] unpublished data, 1999). As a result of underutilization of varicella vaccine, hospitalizations, serious complications, and deaths attributable to varicella infection continue to occur in the United States.4,5 To increase vaccine coverage and reduce the current morbidity and mortality attributable to varicella, the ACIP recently recommended that a physician’s diagnosis of varicella, a reliable history of the disease, serologic evidence of immunity, or receipt of varicella vaccine be required for enrollment in child care centers and schools.3 In addition, Healthy People 2010 objectives for varicella vaccine coverage are more than 90% for children 19 to 35 months of age and more than 95% at school entry.6 Varicella deaths and severe morbidity, as well as the societal disruption of children missing 5 to 7 days of school or child care, have prompted states to consider requirements for varicella immunization for school and child care center entry. Several states and the District of Columbia already have such requirements, and a number of other states have begun the implementation process. Children 12 months of age or older without documentation of varicella immunization or infection who do not have a contraindication should receive a dose of varicella vaccine immediately. In addition, special emphasis should be placed on immunization of susceptible older children and adults, because the likelihood of severe infection increases with increasing age. POTENTIAL BARRIERS TO IMMUNIZATION WITH VARICELLA VACCINE Potential barriers to achieving high rates of varicella immunization among children include the following: 1) the misconception that varicella is uniformly a mild disease; 2) concerns about vaccine effectiveness and safety; 3) concerns about waning immunity; 4) concern that universal immunization of young children will shift the disease burden to older age groups among whom the disease is more severe; 5) the stringent storage and handling requirements of the vaccine; 6) vaccine availability; 7) inadequate insurance coverage; and 8) lack of requirements for varicella vaccine for licensed child care and school entry.7 In addition, there is an inherent lag time between issuance of recommendations and full incorporation of the recommendations into immunization programs. Although some of these issues are no longer barriers to immunization with varicella vaccine, others remain. VARICELLA DISEASE BURDEN Varicella is a common, highly infectious disease that, in the absence of immunization, infects almost every person. Before the availability of the varicella vaccine, approximately 4 million cases occurred annually in the United States, resulting in 10 000 hospitalizations and 100 deaths.5 In the United States, more than 90% of infections, two thirds of varicellarelated hospitalizations, and almost half of varicellarelated deaths occur in children.5 In children, varicella is one of the most important risk factors for severe, invasive, group A streptococcal disease.8,9 Although the incidence of disease among adults is low, the risk of complications and death attributable to The recommendations in this statement do not indicate an exclusive course of treatment or serve as a standard of medical care. Variations, taking into account individual circumstances, may be appropriate. PEDIATRICS (ISSN 0031 4005). Copyright © 2000 by the American Acad-