title: [Unexpectedly high proportion of preschool children immune to hepatitis A virus. Contact tracing investigation shows the need for vaccination prior to traveling abroad].
abstract: Hepatitis A (HAV) is a low incidence infectious disease in Sweden, and a majority of cases in this country are acquired abroad, although domestic cases are not uncommon in the day care setting. We investigated an outbreak of hepatitis A in two day care centres and found that a large proportion (23%) of the 113 unvaccinated preschool children were immune to HAV. This observation indicates that there may have been sub-clinical cases of HAV at the two centres. The results of our study underscore the importance of HAV vaccination in preschool children prior to travel to areas where this disease is common. The findings also highlight the need for up-to-date national seroepidemiological data on HAV immunity in different age groups in Sweden. Studies aimed at obtaining such information could also provide a basis for deciding whether targeted vaccination strategies against HAV are needed in the day care setting.
authors.affiliation: Östersunds sjukhus - AT-läkare Östersund, Sweden Östersunds sjukhus - ÁT-läkare Östersund, Sweden.
authors.forename: Hanna
authors.initials: H
authors.lastname: Persson
authors.affiliation: Östersunds sjukhus - Barn- och ungdomskliniken Östersund, Sweden Mittuniversitet - Omvårdnad och medicinsk vetenskap Östersund, Sweden.
authors.forename: Federico
authors.initials: F
authors.lastname: Nasta
authors.affiliation: Jämtland County Council - Department of Communicable Disease Control and Prevention Östersund, Sweden Jämtland County Council - Department of Communicable Disease Control and Prevention Östersund, Sweden.
authors.forename: Ingrid
authors.initials: I
authors.lastname: Svensson
authors.affiliation: Jämtland County Council - Department of Communicable Disease Control and Prevention Östersund, Sweden Jämtland County Council - Department of Communicable Disease Control and Prevention Östersund, Sweden.
authors.forename: Micael
authors.initials: M
authors.lastname: Widerström
mesh_terms: D000328:Adult; D002648:Child; D002656:Child Day Care Centers; D002675:Child, Preschool; D016358:Contact Tracing; D005190:Family; D005260:Female; D006506:Hepatitis A / Q000097:blood / Q000453:epidemiology / Q000276:immunology* / Q000635:transmission; D022362:Hepatitis A Vaccines; D006508:Hepatitis Antibodies / Q000097:blood; D006801:Humans; D007109:Immunity; D007223:Infant; D008297:Male; D016036:Seroepidemiologic Studies; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology; D014195:Travel; D014611:Vaccination / Q000706:statistics & numerical data
chemical_list: D022362:Hepatitis A Vaccines; D006508:Hepatitis Antibodies