Synopsis: During week 16 (April 14-20, 2013), influenza activity decreased in the United States. o Viral Surveillance : Of 3,384 specimens tested and reported by collaborating laboratories, 250 (7.4%) were positive for influenza.

o Pneumonia and Influenza Mortality: The proportion of death sattributed to pneumonia and influenza (P&I) was below the epidemic threshold.

o Influenza-Associated Pediatric Deaths: Five pediatric deaths were reported.

o Influenza-Associated Hospitalizations: Acumulative rate for thes eason of 43.9laboratory-confirmed influenza-associated hospitalizations per 100,000 population wasreported. Of reported hospitalizations, 50% were among adults 65 years and older.

o Outpatient Illness Surveillance : The proportion of outpatient visits for influenza-like illness (ILI) was 1.1%. This is below the national baseline of 2.2%. All 10 regions reported ILI below region-specific baseline levels. One state experienced low activity; 49 states and New York City experienced minimal activity, and the District of Columbia had insufficient data.

o Geographic Spread of Influenza : Three states reported widespread influenza activity; 3 states reported regional influenza activity; 8 states reported local influenza activity; the District of Columbia, Guam, Puerto Rico, and 35 states reported sporadic influenza activity; 1 state reported no influenza activity, and the U.S. Virgin Islands did not report.

Stephen B. Thacker CDC Library collection

United States