摘要：Objectives. The purpose of our study was to more accurately characterize people reporting influenza-like illness (ILI) and evaluate trends in health care seeking and influenza diagnosis and treatment during the 2009 influenza pandemic. Methods. From September 2009 to March 2010, we ascertained ILI (fever with cough or sore throat), health care seeking, and clinical diagnosis and treatment of influenza with influenza antiviral drugs among adults in 51 jurisdictions, and ILI and health care seeking among children in 41 jurisdictions. Results. Among 216 431 adults and 43 511 children, 8.1% and 28.4% reported ILI, respectively. ILI peaked during November interviews and was higher among young people and American Indian/Alaska Natives. Of those with ILI, 40% of adults and 56% of children reported seeking health care; 26% of adults who sought care reported receiving a diagnosis of influenza. Of adults reporting an influenza diagnosis, 36% were treated with influenza antiviral drugs; treatment was highest among adults aged 18 to 49 years. Conclusions. Analysis of ILI data from the Behavioral Risk Factor Surveillance System enabled a better understanding of the factors associated with self-reported ILI, health care seeking, and clinical influenza diagnosis and treatment, and will help inform year-to-year influenza trends. The influenza A (H1N1) pdm09 virus (pH1N1) caused an estimated 61 million infections, 274 000 hospitalizations, and 12 470 deaths in the United States from April 2009 to April 2010. 1 Surveillance systems in place at the start of the pandemic provided data describing patient visits to health care providers for influenza-like illness (ILI) and reports of influenza-associated hospitalizations and deaths. 2 However, no existing influenza surveillance system monitored influenza among community-dwelling individuals outside of the health care system. Community-level surveillance for influenza is important for accurate estimation of the total influenza disease burden, which includes medically attended laboratory-confirmed cases reported to public health, medically attended cases for which diagnostic testing is not performed, and cases for which medical attention is not sought. 3 To better characterize people reporting ILI in the United States and to evaluate trends in health care–seeking behavior and clinical diagnosis and treatment of influenza during the pH1N1 pandemic, the Centers for Disease Control and Prevention used the Behavioral Risk Factor Surveillance System (BRFSS) to collect information on ILI. Although identification of laboratory-confirmed cases of infection would best estimate true influenza burden, community-level surveillance does not routinely include this information. Moreover, because diagnostic testing is not always performed for patients presenting with symptoms of influenza virus infection, ILI has traditionally been used to monitor influenza activity. Temporally, ILI correlates well with the weekly number of positive influenza test results and is a good predictor of infection among patients when influenza is circulating. 4–7 In this article, we describe the design and implementation of a community survey administered via the BRFSS and present surveillance data collected from September 2009 to March 2010 in the United States.
