title: Trial of 2009 influenza A (H1N1) monovalent MF59-adjuvanted vaccine.
abstract: BACKGROUND
  The 2009 pandemic influenza A (H1N1) virus has emerged to cause the first pandemic of the 21st century. Development of effective vaccines is a public health priority.
  
  
  METHODS
  We conducted a single-center study, involving 176 adults, 18 to 50 years of age, to test the monovalent influenza A/California/2009 (H1N1) surface-antigen vaccine, in both MF59-adjuvanted and nonadjuvanted forms. Subjects were randomly assigned to receive two intramuscular injections of vaccine containing 7.5 microg of hemagglutinin on day 0 in each arm or one injection on day 0 and the other on day 7, 14, or 21; or two 3.75-microg doses of MF59-adjuvanted vaccine, or 7.5 or 15 microg of nonadjuvanted vaccine, administered 21 days apart. Antibody responses were measured by means of hemagglutination-inhibition assay and a microneutralization assay on days 0, 14, 21, and 42 after injection of the first dose.
  
  
  RESULTS
  The most frequent local and systemic reactions were pain at the injection site and muscle aches, noted in 70% and 42% of subjects, respectively; reactions were more common with the MF59-adjuvanted vaccine than with nonadjuvanted vaccine. Three subjects reported fever, with a temperature of 38 degrees C or higher, after either dose. Antibody titers, expressed as geometric means, were higher at day 21 among subjects who had received one dose of MF59-adjuvanted vaccine than among those who had received one dose of nonadjuvanted vaccine (P<0.001 by the microneutralization assay). By day 21, hemagglutination-inhibition and microneutralization antibody titers of 1:40 or more were seen in 77 to 96% and 92 to 100% of subjects receiving MF59-adjuvanted vaccine, respectively, and in 63 to 72% and 67 to 76% of those receiving nonadjuvanted vaccine, respectively. By day 42, after two doses of vaccine, hemagglutination-inhibition and microneutralization antibody titers of 1:40 or more were seen in 92 to 100% and 100% of recipients of MF59-adjuvanted vaccine, respectively, and in 74 to 79% and 78 to 83% of recipients of nonadjuvanted vaccine, respectively.
  
  
  CONCLUSIONS
  Monovalent 2009 influenza A (H1N1) MF59-adjuvanted vaccine generates antibody responses likely to be associated with protection after a single dose is administered. (ClinicalTrials.gov number, NCT00943358).
authors.affiliation: Infectious Diseases Unit, University Hospitals Leicester, and Department of Inflammation, Infection and Immunity, University of Leicester, Leicester, United Kingdom.
authors.forename: Tristan W
authors.initials: TW
authors.lastname: Clark
authors.forename: Manish
authors.initials: M
authors.lastname: Pareek
authors.forename: Katja
authors.initials: K
authors.lastname: Hoschler
authors.forename: Helen
authors.initials: H
authors.lastname: Dillon
authors.forename: Karl G
authors.initials: KG
authors.lastname: Nicholson
authors.forename: Nicola
authors.initials: N
authors.lastname: Groth
authors.forename: Iain
authors.initials: I
authors.lastname: Stephenson
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage* / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006389:Hemagglutinins, Viral / Q000276:immunology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D007251:Influenza, Human / Q000276:immunology* / Q000517:prevention & control; D007273:Injections, Intramuscular; D008297:Male; D008875:Middle Aged; D009500:Neutralization Tests; D011136:Polysorbates / Q000008:administration & dosage / Q000009:adverse effects; D013185:Squalene / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology; D055815:Young Adult
chemical_list: D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D006389:Hemagglutinins, Viral; D007252:Influenza Vaccines; C089950:MF59 oil emulsion; D011136:Polysorbates; D013185:Squalene