1122. Progress toward routine estimation of the seasonal burden of influenza in the United States
Session: Poster Abstract Session: Influenza and H1N1 Diagnosis, Epidemiology, and Viral Outcome
Saturday, October 22, 2011
Room: Poster Hall B1
Background: The burden of influenza varies by season, and sources such as death certificate and hospital discharge data lack timeliness in estimating influenza-related hospitalizations and deaths.  To provide more timely estimates of the burden of influenza-related illnesses, hospitalizations and deaths in the United States during the 2009 H1N1 pandemic, CDC developed a probabilistic model using a series of “multipliers” which account for under-ascertainment of influenza. We piloted the collection of additional data to further refine the multipliers used in the model during the 2010/11 influenza season.

Methods: To calculate preliminary burden estimates for the 2010/11 influenza season, we used 2010/11 rates of laboratory-confirmed influenza hospitalization collected through the Emerging Infections Program (EIP) Influenza Surveillance Network.  We extrapolated EIP rates to the US population and corrected using the probabilistic model developed in 2009 to estimate cases, hospitalizations, and deaths.  Five EIP sites are collecting additional data (reviews of in-hospital influenza testing, influenza sentinel surveillance, and physician and community surveys) to improve the accuracy of the multipliers by age for a non-pandemic season.

Results: From October 1, 2010 – April 30, 2011, preliminary burden estimates include: 27 million influenza-associated illnesses (range: 26-29 million) in the US, with 187,000 hospitalizations (range: 175,000-194,000) and 3,800 deaths (range: 2,800-4,800).  We will evaluate the multipliers and make final estimates at the end of the season when additional data collection is completed. 

Conclusion: Timely estimates of the annual influenza burden can provide public health officials with information to evaluate annual programs and allocate resources.  Preliminary estimates for 2010/11 were calculated with multiplier values from the pandemic, and could reflect a conservative estimate of the burden if decreased public attention on influenza led to lower levels of influenza ascertainment and reporting. Additional data being collected in the first post-pandemic season will help refine our probabilistic model and allow for more accurate assessment of the annual burden of influenza. 


Subject Category: V. Virology including clinical and basic studies of viral infections, including hepatitis

Carrie Reed, ScD1, Martin I. Meltzer, PhD, MS1, Pamala Daily Kirley, MPH2, Ruth Emerson2, Deborah Aragon, MSPH3, Emily B. Hancock, MS4, Lisa Butler4, Joan Baumbach, MD, MPH4, Gary Hollick, PhD5, Nancy Bennett, MD, MS5, Elena Phoutrides6, Matthew Laidler, MPH, MA6 and Lyn Finelli, DrPH, MS1, (1)Centers for Disease Control and Prevention, Atlanta, GA, (2)California Emerging Infections Program, Oakland, CA, (3)Communicable Disease, Epidemiology Program, Colorado Department of Public Health, Denver, CO, (4)Emerging Infections Program, NM State Department of Health, Santa Fe, NM, (5)Emerging Infections Program, University of Rochester Medical Center, Rochester, NY, (6)Emerging Infections Program, Oregon Department of Human Services, Portland, OR

Disclosures:

C. Reed, None

M. I. Meltzer, None

P. Daily Kirley, None

R. Emerson, None

D. Aragon, None

E. B. Hancock, None

L. Butler, None

J. Baumbach, None

G. Hollick, None

N. Bennett, None

E. Phoutrides, None

M. Laidler, None

L. Finelli, None

Findings in the abstracts are embargoed until 12:01 a.m. EST Thursday, Oct. 20 with the exception of research findings presented at IDSA press conferences.