title: Effectiveness of one and two doses of varicella vaccine in preventing laboratory-confirmed cases in children in Navarre, Spain.
abstract: Varicella vaccine effectiveness was evaluated in a case-control study in Navarre, Spain, in 2010-2012. The cases were 54 children aged 15 months to 10 years with a diagnosis of varicella confirmed by polymerase-chain-reaction. Each case was matched with eight controls by pediatric practice, district of residence and date of birth. The effectiveness was 87% (95% confidence interval: 60% to 97%) for one dose of vaccine and 97% (80% to 100%) for two doses. A single dose was 93% (34% to 100%) effective in the first year, which declined to 61% (95% CI: -64% to 94%) after the third year. In conclusion, varicella vaccine is highly effective in preventing confirmed cases, although this effect declines over time since the first dose. A second dose helps to reestablish very high levels of effectiveness and to reduce the risk of breakthrough varicella.
authors: Instituto de Salud Pública de Navarra; Pamplona, Spain; CIBER Epidemiología y Salud Pública (CIBERESP); Pamplona, Spain.
authors: Manuel García
authors: MG
authors: Cenoz
authors: Víctor
authors: V
authors: Martínez-Artola
authors: Marcela
authors: M
authors: Guevara
authors: Carmen
authors: C
authors: Ezpeleta
authors: Aurelio
authors: A
authors: Barricarte
authors: Jesús
authors: J
authors: Castilla
mesh_terms: D016022:Case-Control Studies; D002644:Chickenpox / Q000453:epidemiology* / Q000517:prevention & control*; D019433:Chickenpox Vaccine / Q000008:administration & dosage*; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D013030:Spain / Q000453:epidemiology; D016896:Treatment Outcome; D014611:Vaccination / Q000379:methods*
chemical_list: D019433:Chickenpox Vaccine
keywords: breakthrough varicella; vaccine effectiveness; varicella; varicella vaccine; varicella-zoster virus