Synopsis: During week 5 (February 1-7, 2015), influenza activity decreased, but remained elevated in the United States.

o Viral Surveillance: Of 21,340 specimens tested and reported by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories during week 5, 3,174 (14.9%) 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: Eleven influenza-associated pediatric deaths were reported.

o Influenza-associated Hospitalizations: A cumulative rate for the season of 44.1 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.

o Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 3.8%, above the national baseline of 2.0%. All 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and 15 states experienced high ILI activity; New York City and 15 states experienced moderate ILI activity; eight states experienced low ILI activity; 12 states experienced minimal ILI activity; and the District of Columbia had insufficient data.

o Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 32 states was reported as widespread; Guam, the U.S. Virgin Islands, and 16 states reported regional activity; and the District of Columbia and two states reported local activity.

Stephen B. Thacker CDC Library collection

United States