title: Effectiveness of seasonal influenza vaccine against pandemic (H1N1) 2009 virus, Australia, 2010.
abstract: To estimate effectiveness of seasonal trivalent and monovalent influenza vaccines against pandemic influenza A (H1N1) 2009 virus, we conducted a test-negative case-control study in Victoria, Australia, in 2010. Patients seen for influenza-like illness by general practitioners in a sentinel surveillance network during 2010 were tested for influenza; vaccination status was recorded. Case-patients had positive PCRs for pandemic (H1N1) 2009 virus, and controls had negative influenza test results. Of 319 eligible patients, test results for 139 (44%) were pandemic (H1N1) 2009 virus positive. Adjusted effectiveness of seasonal vaccine against pandemic (H1N1) 2009 virus was 79% (95% confidence interval 33%-93%); effectiveness of monovalent vaccine was 47% and not statistically significant. Vaccine effectiveness was higher among adults. Despite some limitations, this study indicates that the first seasonal trivalent influenza vaccine to include the pandemic (H1N1) 2009 virus strain provided significant protection against laboratory-confirmed pandemic (H1N1) 2009 infection.
authors.affiliation: Victorian Infectious Diseases Reference Laboratory, North Melbourne, Victoria, Australia. james.fielding@mh.org.au
authors.forename: James E
authors.initials: JE
authors.lastname: Fielding
authors.forename: Kristina A
authors.initials: KA
authors.lastname: Grant
authors.forename: Katherine
authors.initials: K
authors.lastname: Garcia
authors.forename: Heath A
authors.initials: HA
authors.lastname: Kelly
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001315:Australia; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005260:Female; D019267:Hemagglutinin Glycoproteins, Influenza Virus / Q000032:analysis; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology / Q000276:immunology / Q000517:prevention & control* / Q000821:virology; D008297:Male; D008875:Middle Aged; D058873:Pandemics / Q000517:prevention & control*; D016133:Polymerase Chain Reaction; D012621:Seasons; D018571:Sentinel Surveillance; D016896:Treatment Outcome; D014611:Vaccination
chemical_list: C543345:H1N1 virus hemagglutinin; D019267:Hemagglutinin Glycoproteins, Influenza Virus; D007252:Influenza Vaccines