Weekly U.S. Influenza Surveillance Report

All data are preliminary and may change as more reports are received.

During week 9 (March 1-7, 2015), influenza activity continued to decrease, but remained elevated in the United States.

Viral Surveillance: Of 14,634 specimens tested and reported by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories during week 9, 1,670 (11.4%) were positive for influenza.
Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the epidemic threshold.
Influenza-associated Pediatric Deaths: Seven influenza-associated pediatric deaths were reported.
Influenza-associated Hospitalizations: A cumulative rate for the season of 55.7 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported.
Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.4%, above the national baseline of 2.0%. Eight regions reported ILI at or above region-specific baseline levels. Puerto Rico and six states experienced high ILI activity; one state experienced moderate ILI activity; 13 states experienced low ILI activity; New York City and 30 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
Geographic Spread of Influenza: The geographic spread of influenza in nine states was reported as widespread; Guam, Puerto Rico, the U.S. Virgin Islands, and 29 states reported regional activity; 11 states reported local activity; and the District of Columbia and one state reported sporadic activity.