Synopsis: During week 11 (March 10 – 16, 2013), influenza activity remained elevated in the United States, but decreased in most areas. o Viral Surveillance: Of 5,526 specimens tested and reported by collaborating laboratories, 899 (16.3%) were positive for influenza. o Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the epidemic threshold. o Influenza-Associated Pediatric Deaths: Six pediatric deaths were reported. o Influenza-Associated Hospitalizations: A cumulative rate for the season of 40.6 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. Of reported hospitalizations, 51% were among adults 65 years and older. o Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.2%. This is at the national baseline of 2.2%. Three of 10 regions reported ILI above region-specific baseline levels. One state experienced high ILI activity; 5 states experienced moderate activity; 6 states and New York City experienced low activity; 38 states experienced minimal activity, and the District of Columbia had insufficient data. o Geographic Spread of Influenza: Seven states reported widespread influenza activity; Puerto Rico and 8 states reported regional influenza activity; 26 states reported local influenza activity; 9 states reported sporadic influenza activity; Guam reported no influenza activity, and the U.S. Virgin Islands and the District of Columbia did not report.

Stephen B. Thacker CDC Library collection