title: Determinants of varicella breakthrough: results of a 2012 case control study.
abstract: This study aims to evaluate the determinants of breakthrough infection after one dose of varicella vaccine. We designed a retrospective case-control study. Breakthrough cases were children, aged 1-15, who presented varicella symptoms ≥ 42 days after the first dose of varicella vaccine (breakthrough). Controls were children, aged 1-15 years, who attended the same class (in a school or in a kindergarten) than the cases in the year of the breakthrough onset; they received a dose of varicella vaccine ≥ 42 days before the case rash onset and they did not develop varicella symptoms. We enrolled 45 cases and 135 controls. 40% of cases (n = 18; 95% CI = 25.4-54.6) presented at least one risk factor; this proportion was 39.2% (95% CI = 30.9-47.6) among the controls (chi-square = 0.0078; P = 0.93). Time between vaccination and virus exposure was longer among cases. Logistic regression showed that breakthrough disease was associated with duration of time from vaccination.
authors.affiliation: Department of Biomedical Science and Human Oncology; Aldo Moro University of Bari; Bari, Italy.
authors.forename: Silvio
authors.initials: S
authors.lastname: Tafuri
authors.affiliation: Department of Biomedical Science and Human Oncology; Aldo Moro University of Bari; Bari, Italy.
authors.forename: Rocco
authors.initials: R
authors.lastname: Guerra
authors.affiliation: Department of Biomedical Science and Human Oncology; Aldo Moro University of Bari; Bari, Italy.
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Cappelli
authors.affiliation: Department of Medical and Surgical Science; University of Foggia; Foggia, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Martinelli
authors.affiliation: Department of Medical and Surgical Science; University of Foggia; Foggia, Italy.
authors.forename: Rosa
authors.initials: R
authors.lastname: Prato
authors.affiliation: Department of Biomedical Science and Human Oncology; Aldo Moro University of Bari; Bari, Italy.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Germinario
mesh_terms: D000293:Adolescent; D016022:Case-Control Studies; D002644:Chickenpox / Q000453:epidemiology* / Q000276:immunology* / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D007558:Italy / Q000453:epidemiology; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors
keywords: UMV; breakthrough; vaccine failure; varicella; varicella vaccine schedule