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Influenza Hospitalization Surveillance


InfluenzaActive surveillance for hospitalized laboratory–confirmed influenza cases among Rochester area residents has been conducted since 2004. Laboratory-confirmed influenza is reportable to the New York State Department of Public Health; EIP staff collect data to determine underlying conditions, influenza testing patterns, and markers of disease severity.

Goals and Objectives

  • Determine the age-specific rates of laboratory confirmed influenza associated hospitalization.
  • Determine the rate of serious influenza-associated complications, such as secondary bacterial infections, and the need for ICU admission/mechanical ventilation.
  • Identify factors that are associated with severe illness or influenza-associated complications.
  • Evaluate adherence to influenza vaccination recommendations.


Active surveillance for laboratory-confirmed influenza hospitalizations is conducted among residents of the seven county Rochester catchment area. A case is defined as a resident in the catchment area having a hospital admission with a laboratory confirmed influenza infection. Demographic, diagnostic, medical and vaccination histories are collected from the medical charts of cases and are recorded on a standardized case report form.

Comprehensive and aggregate data analyses for this project are ongoing and available at the following websites:


The incidence of influenza hospitalizations varies each season and by age group, depending on what strain of influenza is most prominent and the efficacy of the vaccine.

Graph of influenza hospitalization incidence

Selected Publications

  • Arriola CS, Garg S, Anderson EJ, Ryan PA, George A, Zansky SM, Bennett N, Reingold A, Bargsten M, Miller L, Yousey-Hindes K, Tatham L, Bohm SR, Lynfield R, Thomas A, Lindegren ML, Schaffner W, Fry AM, Chaves SS.  Influenza vaccination modifies disease severity among community-dwelling adults hospitalized with influenza. Clin Infect Dis. 2017 May 19. doi: 10.1093/cid/cix468. [Epub ahead of print] Link:
  • Appiah GD, Chaves SS, Kirley PD, Miller L, Meek J, Anderson E, Oni O, Ryan P, Eckel S, Lynfield R, Bargsten M, Zansky SM, Bennett N, Lung K, McDonald-Hamm C, Thomas A, Brady D, Lindegren ML, Schaffner W, Hill M, Garg S, Fry AM, Campbell AP. Increased antiviral treatment among hospitalized children and adults with laboratory-confirmed influenza, 2010-2015. Clin Infect Dis. 2017 Feb 1;64(3):364-367. Link:
  • Havers F, Sokolow L, Shay DK, Farley MM, Monroe M, Meek J, Daily Kirley P, Bennett NM, Morin C, Aragon D, Thomas A, Schaffner W, Zansky SM, Baumbach J, Ferdinands J, Fry AM.  Case-control study of vaccine effectiveness in preventing laboratory-confirmed influenza hospitalizations in older adults, United States, 2010-2011. Clin Infect Dis. 2016 Nov 15;63(10):1304-1311. Link: