Self-Reported Influenza-like Illness During the 2009 H1N1 Influenza Pandemic—United States, September 2009–March 2010

During the first 3 months of H1N1 influenza outbreak, approximately 43,000 cases were reported to CDC. In Jun 2009, the World Health Organization declared the outbreak an influenza pandemic. Because no existing influenza surveillance system in the US monitored influenza-like illness (ILI) among persons with ILI who didn't seek health care, CDC initiated community-based surveillance of self-reported ILI and health-care--seeking behavior through a supplementary module of the Behavioral Risk Factor Surveillance System (BRFSS). Here, Biggerstaff et al provide a summary of the results from BRFSS surveys conducted during Sep 2009-Mar 2010. A CDC editorial note is included.