Disease Burden of Influenza
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The severity of influenza disease in the United States can vary widely and is determined by a number of things including the characteristics of circulating viruses, the timing of the season, how well the vaccine is working to protect against illness, and how many people got vaccinated. CDC tracks severity principally through its national Influenza Surveillance System that monitors key indicators like the percentage of deaths resulting from pneumonia or influenza, rates of influenza-associated hospitalizations, pediatric deaths and the percentage of visits to outpatient clinics for influenza-like illness. In addition to using surveillance data, CDC uses mathematical models to fill in the picture of the disease burden and the impact of influenza immunization programs. Models are used to augment surveillance because most of the surveillance systems only look at portions of the U.S. population and in some cases there can be significant under-reporting of influenza deaths and hospitalizations. This page includes links to key resources on the burden of influenza.
While the impact of flu varies, it places a substantial burden on the health of people in the United States each year. CDC estimates that influenza has resulted in between 9.2 million and 35.6 million illnesses, between 140,000 and 710,000 hospitalizations and between 12,000 and 56,000 deaths annually since 2010.
Flu-related Illness and Hospitalization
- Seasonal Influenza-Associated Hospitalizations in the United States
- Flu Activity and Surveillance
- Thompson WW, Shay DK, Weintraub E, Brammer L, Bridges CB, Cox NJ, Fukuda K. Influenza-associated hospitalizations in the United States. JAMA. 2004 Sep 15;292(11):1333-40
- Zhou H, Thompson WW, Viboud CG, Ringholz CM, Cheng PY, Steiner C, Abedi GR, Anderson LJ, Brammer L, Shay DK. Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993-2008. Clin Infect Dis. 2012 May;54(10):1427-36
- Flu Activity and Surveillance
- Chaves SS, Lynfield R, Lindegren ML, Bresee J, Finelli L. The US Influenza Hospitalization Surveillance Network. Emerg Infect Dis. 2015 Sep;21(9):1543-50. doi: 10.3201/eid2109.141912.
- CDC Collaborative Study: Influenza Important Cause of Respiratory Hospitalizations Worldwide
- Lafond KE, Nair H, Rasooly MH, Valente F, Booy R et al. Global role and burden of influenza in pediatric respiratory hospitalizations, 1982-2012: A systematic analysis. PLoS Med. 2016 Mar 24;13(3):e1001977. doi: 10.1371/journal.pmed.1001977. eCollection 2016.
Flu-related illness and hospitalization averted by vaccination
2015-2016 season
- Estimated Influenza Illnesses, Medical Visits, Hospitalizations, and Deaths Averted by Vaccination in the United States
- CDC: Flu Vaccine Protected Millions Last Season; Vaccine Coverage Remains Low
2014-2015 season
- Estimated Influenza Illnesses and Hospitalizations Averted by Vaccination — United States, 2014–15 Influenza Season
- Fewer Than Half of Americans Report Having Gotten A Flu Vaccine this Season
2013-2014 season
- CDC. Estimated Influenza Illnesses and Hospitalizations Averted by Vaccination — United States, 2013–14 Influenza Season. MMWR Morb Mortal Wkly Rep 2014; 63(49);1151-1154
- New CDC Report Shows Benefits of Flu Vaccine Last Season But Fewer Than Half of Americans Say They Have Been Vaccinated This Season
2012-2013 season
- CDC. Estimated influenza illnesses and hospitalizations averted by influenza vaccination—United States, 2012–13 influenza season. MMWR Morb Mortal Wkly Rep 2013; 62(49);997-1000
- New Report Cites Benefits of Flu Vaccine Yet More Than Half of Americans Remain Unvaccinated
- Modeling the Effect of Different Vaccine Effectiveness Estimates on the Number of Vaccine-Prevented Influenza-Associated Hospitalizations in Older Adults [135 KB, 4 pages]
- CDC Study Concludes Flu Vaccination Prevents Hospitalizations in Older People
2011-2012 season
- Effectiveness of influenza vaccine for preventing laboratory-confirmed influenza hospitalizations in adults, 2011-2012 influenza season [329 KB, 10 pages]
- Study Shows Flu Vaccination Prevents Hospitalizations in Older Adults
2005-2011 seasons
- Kostova D, Reed C, Finelli L, Cheng PY, Gargiullo PM, Shay DK, Singleton JA, Meltzer MI, Lu P, Bresee JS. Influenza Illness and Hospitalizations Averted by Influenza Vaccination in the United States, 2005-2011. PLoS One. 2013 Jun 19;8(6):e66312
- CDC Study Shows Flu Vaccination Prevents Significant Flu Illness, Doctor’s Visits and Hospitalizations
- New CDC Study: Influenza Vaccination Reduces Risk of Hospitalization By More Than Half Among Seniors
Flu-related Deaths
- Estimating Seasonal Influenza-Associated Deaths in the United States: CDC Study Confirms Variability of Flu
- CDC. Estimates of deaths associated with seasonal influenza—United States, 1976–2007. MMWR Morb Mortal Wkly Rep 2010;59(33):1057–62
- Under-counting of Flu-related Deaths
- Thompson WW, Shay DK, Weintraub E, Brammer L, Cox N, Anderson LJ, Fukuda K. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003; 289(2):179-186
- Flu Activity and Surveillance
Flu-related deaths averted by vaccination
- CDC Study: Flu Vaccine Saved 40,000 Lives During 9 Year Period
- Foppa IM, Cheng PY, Reynolds SB, Shay DK, Carias C, Bresee JS, Kim IK, Gambhir M, Fry AM. Deaths averted by influenza vaccination in the U.S. during the seasons 2005/06 through 2013/14. Vaccine 2015; Mar 23
Economic Impact of Influenza
- Molinari NA, Ortega-Sanchez IR, Messonnier ML, Thompson WW, Wortley PM, Weintraub E, Bridges CB. The annual impact of seasonal influenza in the US: measuring disease burden and costs. Vaccine. 2007 Jun 28;25(27):5086-96
- Business Pulse: Flu Prevention Infographic, “Business Challenges”
Benefits of Flu Vaccination [826 KB, 1 page]
New! GIF Images:
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- Page last reviewed: April 19, 2017
- Page last updated: May 16, 2017
- Content source:
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
- Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs