National Center for Immunization and Respiratory Diseases (U.S.). Influenza Division.

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.

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Stephen B. Thacker CDC Library collection