Ndumbi, PatriciaFreidl, Gudrun SWilliams, Christopher JMårdh, OtiliaVarela Martinez, Maria del CarmenAvellón, AnaFriesema, IngridVennema, HarryBeebeejaun, KazimNgui, Siew LinEdelstein, MichaelSmith-Palmer, AlisonMurphy, NiamhDean, JonathanFaber, MirkoWenzel, JürgenKontio, MiaMüller, LuiseMidgley, Sofie ElisabethSundqvist, LenaEderth, Josefine LundbergRoque-Afonso, Anne-MarieCouturier, ElisabethKlamer, SofiekeRebolledo, JavieraSuin, VanessaAberle, Stephan WSchmid, Danielade Sousa, RitaAugusto, Gonçalo FigueiredoAlfonsi, ValeriaDel Manso, MartinaCiccaglione, Anna RitaMellou, KassianiHadjichristodoulou, ChristosDonachie, AlastairBorg, Maria-LouiseSočan, MajaPoljak, MarioSeveri, Ettore2020-11-172020-11-172018European Centre for Disease Prevention and Controlhttp://hdl.handle.net/20.500.12105/11358Between 1 June 2016 and 31 May 2017, 17 European Union (EU) and European Economic Area countries reported 4,096 cases associated with a multi-country hepatitis A (HA) outbreak. Molecular analysis identified three co-circulating hepatitis A virus (HAV) strains of genotype IA: VRD_521_2016, V16-25801 and RIVM-HAV16-090. We categorised cases as confirmed, probable or possible, according to the EU outbreak case definitions. Confirmed cases were infected with one of the three outbreak strains. We investigated case characteristics and strain-specific risk factors for transmission. A total of 1,400 (34%) cases were confirmed; VRD_521_2016 and RIVM-HAV16-090 accounted for 92% of these. Among confirmed cases with available epidemiological data, 92% (361/393) were unvaccinated, 43% (83/195) travelled to Spain during the incubation period and 84% (565/676) identified as men who have sex with men (MSM). Results depict an HA outbreak of multiple HAV strains, within a cross-European population, that was particularly driven by transmission between non-immune MSM engaging in high-risk sexual behaviour. The most effective preventive measure to curb this outbreak is HAV vaccination of MSM, supplemented by primary prevention campaigns that target the MSM population and promote protective sexual behaviour.engVoRhttp://creativecommons.org/licenses/by/4.0/Hepatitis AHepatitis A virusMen who have sex with men - MSMSexually transmitted infectionsVaccine-preventable diseasesVaccines and immunisationDisease OutbreaksAdolescentAdultAgedAtribución 4.0 Internacional30131095233310.2807/1560-7917.ES.2018.23.33.17006411560-7917Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletinopen access