title: Second varicella infections: are they more common than previously thought?
abstract: OBJECTIVE
  To describe the epidemiology and clinical characteristics of varicella reinfections reported to a surveillance project.
  
  
  METHODS
  We investigated varicella cases reported to a surveillance project between January 1, 1995, and December 31, 1999--with more extensive investigation of cases reporting previous varicella with onset between January 1, 1998, and September 30, 1998--to provide a more detailed description of first and second varicella infections. A simple decision tree was used to assess the likelihood that reported first and second infections were varicella.
  
  
  RESULTS
  Among varicella cases reported to the surveillance project, 4.5% of cases in 1995 and 13.3% of cases in 1999 reported previous varicella. More than 95% of first infections were physician diagnosed, epidemiologically linked to another case, or had a rash description consistent with varicella; the same was true for reported second infections. People who reported reinfections were generally healthy. There was a family history of repeat infections in 45% of people who reported reinfections.
  
  
  CONCLUSIONS
  Clinical varicella reinfections may occur more commonly than previously thought. Additional studies of the predictive value of a positive varicella history and laboratory studies of reported reinfections are indicated to guide varicella vaccination policy.
authors.affiliation: Department of Epidemiology, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Hall
authors.forename: Teresa
authors.initials: T
authors.lastname: Maupin
authors.forename: Jane
authors.initials: J
authors.lastname: Seward
authors.forename: Aisha O
authors.initials: AO
authors.lastname: Jumaan
authors.forename: Carol
authors.initials: C
authors.lastname: Peterson
authors.forename: Gary
authors.initials: G
authors.lastname: Goldman
authors.forename: Laurene
authors.initials: L
authors.lastname: Mascola
authors.forename: Melinda
authors.initials: M
authors.lastname: Wharton
mesh_terms: D000293:Adolescent; D000367:Age Factors; D002140:California / Q000453:epidemiology; D002644:Chickenpox / Q000175:diagnosis / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D017589:Immunization Programs; D007223:Infant; D008297:Male; D011159:Population Surveillance; D015995:Prevalence; D012008:Recurrence