title: Assessment of potential public health impact of a quadrivalent inactivated influenza vaccine in Thailand.
abstract: BACKGROUND
  Each year, an influenza B strain representing only one influenza B lineage is included in the trivalent inactivated influenza vaccine (IIV3); a mismatch between the selected lineage and circulating viruses can result in suboptimal vaccine effectiveness. We modeled the added potential public health impact of a quadrivalent inactivated influenza vaccine (IIV4) that includes strains from both influenza B lineages compared to IIV3 on influenza-associated morbidity and mortality in Thailand.
  
  
  METHODS
  Using data on the incidence of influenza-associated hospitalizations and deaths, vaccine effectiveness, and vaccine coverage from the 2007-2012 influenza seasons in Thailand, we estimated rates of influenza-associated outcomes that might be averted using IIV4 instead of IIV3. We then applied these rates to national population estimates to calculate averted illnesses, hospitalizations, and deaths for each season. We assumed that the influenza B lineage included in IIV3 would provide a relative vaccine effectiveness of 75% against the other B lineage.
  
  
  RESULTS
  Compared to use of IIV3, use of IIV4 might have led to an additional reduction ranging from 0·4 to 14·3 influenza-associated illnesses per 100 000 population/year, <0·1 to 0·5 hospitalizations per 100 000/year, and <0·1 to 0·4 deaths per 1000/year. Based on extrapolation to national population estimates, replacement of IIV3 with IIV4 might have averted an additional 267-9784 influenza-associated illnesses, 9-320 hospitalizations, and 0-3 deaths.
  
  
  CONCLUSIONS
  Compared to use of IIV3, IIV4 has the potential to further reduce the burden of influenza-associated morbidity and mortality in Thailand.
authors.affiliation: Influenza Program, Thailand Ministry of Public Health - U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.
authors.forename: Wanitchaya
authors.initials: W
authors.lastname: Kittikraisak
authors.affiliation: National Institute of Health, Ministry of Public Health, Nonthaburi, Thailand.
authors.forename: Malinee
authors.initials: M
authors.lastname: Chittaganpitch
authors.affiliation: International Emerging Infections Program, Thailand Ministry of Public Health - U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.|Division of Global Health Protection, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Gregory
authors.affiliation: Bureau of Epidemiology, Ministry of Public Health, Nonthaburi, Thailand.
authors.forename: Yongjua
authors.initials: Y
authors.lastname: Laosiritaworn
authors.affiliation: Bureau of General Communicable Diseases, Ministry of Public Health, Nonthaburi, Thailand.
authors.forename: Thanawadee
authors.initials: T
authors.lastname: Thantithaveewat
authors.affiliation: Influenza Division, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Fatimah S
authors.initials: FS
authors.lastname: Dawood
authors.affiliation: Influenza Program, Thailand Ministry of Public Health - U.S. Centers for Disease Control and Prevention Collaboration, Nonthaburi, Thailand.|Influenza Division, U.S. Centers for Disease Control and Prevention, Atlanta, GA, USA.
authors.forename: Kim A
authors.initials: KA
authors.lastname: Lindblade
mesh_terms: D000914:Antibodies, Viral / Q000097:blood; D017281:Cost of Illness; D006760:Hospitalization; D006801:Humans; D009981:Influenza B virus / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000191:economics / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology / Q000401:mortality / Q000517:prevention & control* / Q000821:virology*; D015233:Models, Statistical; D011634:Public Health; D012621:Seasons; D013785:Thailand / Q000453:epidemiology; D015164:Vaccines, Inactivated / Q000008:administration & dosage
chemical_list: D000914:Antibodies, Viral; D007252:Influenza Vaccines; D015164:Vaccines, Inactivated
keywords: Inactivated influenza vaccine; Thailand; quadrivalent; trivalent