title: Safety and Immunogenicity of a Subvirion Monovalent Unadjuvanted Inactivated Influenza A(H3N2) Variant Vaccine in Healthy Persons ≥18 Years Old.
abstract: BACKGROUND
  Variant influenza A(H3N2) viruses (H3N2v) have transmitted recently from pigs to humans in the United States. Vaccines strategies are needed.
  
  
  METHODS
  Healthy adults received 2 doses of subvirion H3N2v vaccine (15 µg of hemagglutinin/dose) 21 days apart in this open-label trial. Serum hemagglutination inhibition (HAI) and neutralizing (Neut) antibody (Ab) titers were measured before and 8 and 21 days after each dose. Memory B-cell (MBC) responses were assessed.
  
  
  RESULTS
  Vaccine was well tolerated. A total of 40% of subjects had an HAI Ab titer of ≥40 before vaccination. Eight-seven percent (95% confidence interval [CI], 79%-93%) and 73% (95% CI, 63%-81%) of subjects 18-64 years old (98 subjects) and ≥65 years old (90 subjects), respectively, had an HAI titer of ≥40 21 days after dose 1 (P = .01); 51% (95% CI, 41%-61%) and 52% (95% CI, 41%-62%) of younger and older subjects, respectively, developed ≥4-fold rises in titer (P = not significant). Neut Ab response patterns were similar. Geometric mean titers were higher in younger subjects. Dose 2 provided no significant enhancement in responses. Cross-reactive MBCs were detected before vaccination and expanded after vaccination. Preexisting H3N2v-specific MBCs positively correlated with early increases in vaccine-induced Ab.
  
  
  CONCLUSIONS
  In most healthy adults, one 15-µg dose of vaccine elicited levels of HAI Abs associated with protection. Studies in children and elderly individuals are indicated to define the immunization needs of these groups.
  
  
  BACKGROUND
  NCT01746082.
authors: Department of Molecular Virology & Microbiology Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors: Wendy A
authors: WA
authors: Keitel
authors: Group Health Research Institute, Seattle, Washington.
authors: Lisa A
authors: LA
authors: Jackson
authors: The Hope Clinic of the Emory Vaccine Center Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia.
authors: Srilatha
authors: S
authors: Edupuganti
authors: Department of Internal Medicine, University of Iowa Iowa City VA Health System, Iowa City.
authors: Patricia L
authors: PL
authors: Winokur
authors: The Hope Clinic of the Emory Vaccine Center Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia.
authors: Mark J
authors: MJ
authors: Mulligan
authors: Vanderbilt Vaccine Center Department of Pathology, Microbiology and Immunology Department of Pediatrics, Vanderbilt University, Nashville, Tennessee.
authors: Natalie J
authors: NJ
authors: Thornburg
authors: Department of Molecular Virology & Microbiology Department of Medicine, Baylor College of Medicine, Houston, Texas.
authors: Shital M
authors: SM
authors: Patel
authors: The Hope Clinic of the Emory Vaccine Center Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia.
authors: Nadine G
authors: NG
authors: Rouphael
authors: The Hope Clinic of the Emory Vaccine Center Department of Medicine, Division of Infectious Diseases, Emory University School of Medicine, Atlanta, Georgia.
authors: Lilin
authors: L
authors: Lai
authors: Vanderbilt Vaccine Center Department of Pathology, Microbiology and Immunology Department of Pediatrics, Vanderbilt University, Nashville, Tennessee.
authors: Sandhya
authors: S
authors: Bangaru
authors: Cincinnati Children's Hospital Medical Center, University of Cincinnati, Ohio.
authors: Monica M
authors: MM
authors: McNeal
authors: EMMES Corporation, Rockville, Maryland.
authors: Abbie R
authors: AR
authors: Bellamy
authors: EMMES Corporation, Rockville, Maryland.
authors: Heather R
authors: HR
authors: Hill
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000914:Antibodies, Viral / Q000097:blood*; D001402:B-Lymphocytes / Q000276:immunology; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D053122:Influenza A Virus, H3N2 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000276:immunology*; D007251:Influenza, Human / Q000517:prevention & control*; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007252:Influenza Vaccines
keywords: H3N2 variant; immune responses; immunization; influenza; pandemic
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