title: Estimating the potential effects of a vaccine program against an emerging influenza pandemic--United States.
abstract: BACKGROUND
  Human illness from influenza A(H7N9) was identified in March 2013, and candidate vaccine viruses were soon developed. To understand factors that may impact influenza vaccination programs, we developed a model to evaluate hospitalizations and deaths averted considering various scenarios.
  
  
  METHODS
  We utilized a model incorporating epidemic curves with clinical attack rates of 20% or 30% in a single wave of illness, case hospitalization ratios of 0.5% or 4.2%, and case fatality ratios of 0.08% or 0.53%. We considered scenarios that achieved 80% vaccination coverage, various starts of vaccination programs (16 or 8 weeks before, the same week of, or 8 or 16 weeks after start of pandemic), an administration rate of 10 or 30 million doses per week (the latter rate is an untested assumption), and 2 levels of vaccine effectiveness (2 doses of vaccine required; either 62% or 80% effective for persons aged <60 years, and either 43% or 60% effective for persons aged ≥ 60 years).
  
  
  RESULTS
  The start date of vaccination campaigns most influenced impact; 141,000-2,200,000 hospitalizations and 11,000-281,000 deaths were averted when campaigns started before a pandemic, and <100-1 300,000 hospitalizations and 0-165,000 deaths were averted for programs beginning the same time as or after the introduction of the pandemic virus. The rate of vaccine administration and vaccine effectiveness did not influence campaign impact as much as timing of the start of campaign.
  
  
  CONCLUSIONS
  Our findings suggest that efforts to improve the timeliness of vaccine production will provide the greatest impacts for future pandemic vaccination programs.
authors: Epidemiology and Prevention Branch, Influenza Division.
authors: Matthew
authors: M
authors: Biggerstaff
authors: Epidemiology and Prevention Branch, Influenza Division.
authors: Carrie
authors: C
authors: Reed
authors: Modeling Unit and Office of the Director, and.
authors: David L
authors: DL
authors: Swerdlow
authors: Modeling Unit, National Center for Immunization and Respiratory Diseases (NCIRD), Centers for Disease Control and Prevention (CDC), Atlanta, Georgia Epidemiological Modelling Unit, Department of Epidemiology and Preventive Medicine, Monash University, Melbourne, Australia.
authors: Manoj
authors: M
authors: Gambhir
authors: Immunization Services Division, NCIRD.
authors: Samuel
authors: S
authors: Graitcer
authors: Epidemiology and Prevention Branch, Influenza Division.
authors: Lyn
authors: L
authors: Finelli
authors: Scientific and Program Services Branch, Division of Preparedness and Emerging Infections, National Center for Emerging and Zoonotic Infectious Diseases.
authors: Rebekah H
authors: RH
authors: Borse
authors: Influenza Coordination Unit, Office of Infectious Diseases, CDC, Atlanta, Georgia.
authors: Sonja A
authors: SA
authors: Rasmussen
authors: Scientific and Program Services Branch, Division of Preparedness and Emerging Infections, National Center for Emerging and Zoonotic Infectious Diseases.
authors: Martin I
authors: MI
authors: Meltzer
authors: Immunization Services Division, NCIRD.
authors: Carolyn B
authors: CB
authors: Bridges
mesh_terms: D021821:Communicable Diseases, Emerging / Q000517:prevention & control*; D004189:Disaster Planning / Q000379:methods*; D062665:Epidemiological Monitoring; D006801:Humans; D017589:Immunization Programs / Q000458:organization & administration*; D064766:Influenza A Virus, H7N9 Subtype; D007252:Influenza Vaccines / Q000008:administration & dosage*; D007251:Influenza, Human / Q000517:prevention & control*; D008962:Models, Theoretical; D058873:Pandemics / Q000517:prevention & control*; D014481:United States / Q000453:epidemiology
chemical_list: D007252:Influenza Vaccines
keywords: influenza; influenza A(H7N9); influenza vaccine; mathematical modeling; pandemic