title: Oseltamivir-resistant influenza virus A (H1N1), Europe, 2007-08 season.
abstract: In Europe, the 2007-08 winter season was dominated by influenza virus A (H1N1) circulation through week 7, followed by influenza B virus from week 8 onward. Oseltamivir-resistant influenza viruses A (H1N1) (ORVs) with H275Y mutation in the neuraminidase emerged independently of drug use. By country, the proportion of ORVs ranged from 0% to 68%, with the highest proportion in Norway. The average weighted prevalence of ORVs across Europe increased gradually over time, from near 0 in week 40 of 2007 to 56% in week 19 of 2008 (mean 20%). Neuraminidase genes of ORVs possessing the H275Y substitution formed a homogeneous subgroup closely related to, but distinguishable from, those of oseltamivir-sensitive influenza viruses A (H1N1). Minor variants of ORVs emerged independently, indicating multiclonal ORVs. Overall, the clinical effect of ORVs in Europe, measured by influenza-like illness or acute respiratory infection, was unremarkable and consistent with normal seasonal activity.
authors.affiliation: Netherlands Institute for Health Services Research, Utrecht, the Netherlands.
authors.forename: Adam
authors.initials: A
authors.lastname: Meijer
authors.forename: Angie
authors.initials: A
authors.lastname: Lackenby
authors.forename: Olav
authors.initials: O
authors.lastname: Hungnes
authors.forename: Bruno
authors.initials: B
authors.lastname: Lina
authors.forename: Sylvie
authors.initials: S
authors.lastname: van-der-Werf
authors.forename: Brunhilde
authors.initials: B
authors.lastname: Schweiger
authors.forename: Matthias
authors.initials: M
authors.lastname: Opp
authors.forename: John
authors.initials: J
authors.lastname: Paget
authors.forename: Jan
authors.initials: J
authors.lastname: van-de-Kassteele
authors.forename: Alan
authors.initials: A
authors.lastname: Hay
authors.forename: Maria
authors.initials: M
authors.lastname: Zambon