Varicella vaccine has been recommended for use in children 12 months of age and older since 1995. Additional recommendations since that time include the following: (1) pediatric postexposure vaccination within three to five days; (2) use for outbreak control; (3) prevention of infection in children with human immunodeficiency virus infection and age-specific CD4 T lymphocyte percentages of 25 percent, and (4) susceptible persons 13 years and older.
Seward reviewed the five-year experience with the varicella vaccine. The most common adverse effect was local reaction at the injection site. Fever and generalized rash, which occurred in controlled studies, were less common than was anticipated. Serious adverse events were rare, consisting mainly of reactivation of the vaccine virus to cause herpes zoster in both healthy and immunocompromised children and development of pneumonia and hepatitis in severely immunocompromised children who were inappropriately immunized.
Vaccine efficacy is at least 95 percent for prevention of serious disease, 70 to 91 percent for prevention of all disease, and high for prevention or attenuation of varicella infection when given to susceptible patients within three to five days of exposure. The incidence of disease and hospitalization because of severe disease has dropped markedly in communities where the vaccine coverage of children is around 70 percent. Disease occurring in vaccinated persons has fewer systemic symptoms and complications.
Rates of administration have been increasing but still vary widely from region to region. All states have not yet instituted day care and school requirements for varicella vaccine.
Seward concludes that experience with varicella vaccine in the United States demonstrates its safety and efficacy. To further reduce morbidity and mortality from varicella, physicians should obtain a documented history of varicella or evidence of immunity or vaccination for each patient.