title: Persistence and avidity maturation of antibodies to A(H1N1)pdm09 in healthcare workers following repeated annual vaccinations.
abstract: Healthcare workers are at increased risk of influenza infection through direct patient care, particularly during the early stages of a pandemic. Although influenza vaccination is widely recommended in Healthcare workers, data on long-term immunogenicity of vaccination in healthcare workers are lacking. The present study was designed to assess the persistence of the humoral response after pandemic vaccination as well as the impact of repeated annual vaccination in healthcare workers (n=24). Pandemic influenza vaccination resulted in a significant increase in haemagglutination inhibition (HI) antibody titers with 93-100% of subjects achieving protective titers 21-days post each of the three annual vaccinations. Seroprotective antibodies measured by HI, microneutralization and single radial hemolysis assays were present in 77-94% of healthcare workers 6 months post-vaccination. Repeated vaccination resulted in an increased duration of seroprotective antibodies with seroprotective titers increasing from 35-62% 12 months after 2009 pandemic vaccination to 50-75% 12 months after 2010 vaccination. Furthermore, repeated annual vaccination augmented the avidity of influenza-specific IgG antibodies. In conclusion, we have shown that A(H1N1)pdm09 vaccination induces high seroprotective titers that persist for at least 6 months. We demonstrate that repeated vaccination is beneficial to healthcare workers and results in further avidity maturation of vaccine-induced antibodies.
authors.affiliation: The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway; K.G Jebsen Centre for Influenza Vaccines, Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Synnøve
authors.initials: S
authors.lastname: Eidem
authors.affiliation: The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway; K.G Jebsen Centre for Influenza Vaccines, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Research & Development, Haukeland University Hospital, Bergen, Norway.
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Tete
authors.affiliation: The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway; K.G Jebsen Centre for Influenza Vaccines, Department of Clinical Science, University of Bergen, Bergen, Norway.
authors.forename: Åsne
authors.initials: Å
authors.lastname: Jul-Larsen
authors.affiliation: Health Protection England, London, UK.
authors.forename: Katja
authors.initials: K
authors.lastname: Hoschler
authors.affiliation: Department of Molecular and Developmental Medicine, University of Siena, Siena, Italy.
authors.forename: Emanuele
authors.initials: E
authors.lastname: Montomoli
authors.affiliation: Broegelman Research Laboratory, Department of Clinical Sciences, University of Bergen, Bergen, Norway.
authors.forename: Karl A
authors.initials: KA
authors.lastname: Brokstad
authors.affiliation: The Influenza Centre, Department of Clinical Science, University of Bergen, Bergen, Norway; K.G Jebsen Centre for Influenza Vaccines, Department of Clinical Science, University of Bergen, Bergen, Norway; Department of Research & Development, Haukeland University Hospital, Bergen, Norway. Electronic address: rebecca.cox@uib.no.
authors.forename: Rebecca J
authors.initials: RJ
authors.lastname: Cox
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D000915:Antibody Affinity; D006282:Health Personnel; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D005779:Immunodiffusion; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D008875:Middle Aged; D009500:Neutralization Tests; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines
keywords: Avidity; Healthcare workers; Influenza; Long-term antibody persistence; Repeated vaccination