KEYWORDS:
varicella infection, immunization

BACKGROUND:
Universal varicella immunization of all susceptible, immunocompetant children over 1 year of age is currently recommended. Those children with a "reliable history" of infection are not considered to be susceptible.

OBJECTIVE(S):
To identify those children who do not have protective antibody titers following a history of varicella infection.

METHOD(S):
Immunocompetant children aged 1-5 years with a history of varicella infection were identified by chart review and by parental questioning upon presentation for appointments. Parents were asked at what age the child was infected, who diagnosed the infection, if the rash was vesicular, if it was itchy and the approximate number of skin lesions that were present. Serologic testing was done on those patients whose infection occurred before the age of one year or whose infection was mild (<50 lesions) or moderate (50-250 lesions).

RESULT(S):
A total of 32 patients were enrolled in the study. 30 of these patients underwent serologic testing. Children with a history of mild infection were significantly more likely to have a negative antibody titer than were children with moderate infection (OR=12, p=.027). Children who were reported to have had a rash which was not itchy were significantly more likely than children with an itchy rash to have negative antibody titers (OR conservatively estimated to be 34, p=.001). Infection during the first year of life was not a statistically significant predictor of having a negative titer.

CONCLUSIONS(S):
Children aged 1-5 years of age who have a history of varicella infection that consisted of less than 50 lesions or whose rash was not itchy, should be evaluated to determine their immunity to reinfection. If they have negative antibody titers, they are eligible for immunization against varicella.

LEARNING OBJECTIVES:
To define characteristics of natural varicella infection that may identify children who do not have protective antibody titers and may benefit from immunization.