title: Hepatitis A outbreaks in the vaccination era in Catalonia, Spain.
abstract: Hepatitis A outbreaks have a major impact on public health services and involve case investigation and intervention measures to susceptible contacts. At the end of 1998 a universal vaccination program with a combined hepatitis A+B vaccine was started in Catalonia (Spain) in 12-years-old preadolescents. The objective of this study was to compare the characteristics of hepatitis A outbreaks in the periods before and after the introduction of the preadolescent vaccination program and to estimate the preventable fraction of cases associated to outbreaks. The incidence rates of outbreaks, cases and hospitalization associated with each outbreak were calculated. Two periods were considered: before (1991-1998) and after (2000-2007) the introduction of mass vaccination. The preventable fraction and 95% confidence intervals (CI) of cases associated with outbreaks was calculated. The rate of associated cases with outbreaks was higher in the period before the vaccination program than in the post vaccination period (1.53 per 100,000 person-year vs 1.12 ; p< 0.001), but the rate of hospitalization was greater in the period after the introduction of vaccination program than in the period previous to vaccination (0.70 per million persons-year vs 0.08; p< 0.001). The preventable fraction of cases associated to outbreaks was 19.6%(95%CI 6.7-32.5) in the 0-4 years group and 16.7% (95% CI 6.0-27.5) in the 5-14 years group, but the highest figure (38.6%; 95%CI 21.3-55.9) was observed in the 15-24 years age group. The estimated proportion of cases associated with outbreaks that would theoretically have been prevented with the vaccination program suggests that substantial benefits have been obtained in Catalonia in people aged less than 25 years.
authors.affiliation: Directorate of Public Health, Generalitat of Catalonia, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Martínez
authors.forename: Sonia
authors.initials: S
authors.lastname: Broner
authors.forename: Nuria
authors.initials: N
authors.lastname: Torner
authors.forename: Pere
authors.initials: P
authors.lastname: Godoy
authors.forename: Joan
authors.initials: J
authors.lastname: Batalla
authors.forename: Josep
authors.initials: J
authors.lastname: Alvarez
authors.forename: Irene
authors.initials: I
authors.lastname: Barrabeig
authors.forename: Neus
authors.initials: N
authors.lastname: Camps
authors.forename: Gloria
authors.initials: G
authors.lastname: Carmona
authors.forename: Sofía
authors.initials: S
authors.lastname: Minguell
authors.forename: Rosa
authors.initials: R
authors.lastname: Sala
authors.forename: Joan
authors.initials: J
authors.lastname: Caylà
authors.forename: Angela
authors.initials: A
authors.lastname: Domínguez
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D004196:Disease Outbreaks; D005260:Female; D006506:Hepatitis A / Q000453:epidemiology* / Q000517:prevention & control*; D022362:Hepatitis A Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D017325:Hepatitis B Vaccines / Q000008:administration & dosage / Q000276:immunology; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D013030:Spain / Q000453:epidemiology; D014611:Vaccination / Q000706:statistics & numerical data*; D055815:Young Adult
chemical_list: D022362:Hepatitis A Vaccines; D017325:Hepatitis B Vaccines