Weekly U.S. Influenza Surveillance Report
2016-2017 Influenza Season Week 11 ending March 18, 2017
All data are preliminary and may change as more reports are received.
During week 11 (March 12-18, 2017), influenza activity decreased, but remained elevated in the United States.
- Viral Surveillance: The most frequently identified influenza virus subtype reported by public health laboratories during week 11 was influenza A (H3). The percentage of respiratory specimens testing positive for influenza in clinical laboratories decreased.
- Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
- Influenza-associated Pediatric Deaths: Two influenza-associated pediatric deaths were reported.
- Influenza-associated Hospitalizations: A cumulative rate for the season of 50.4 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 3.2%, which is above the national baseline of 2.2%. Seven of ten regions reported ILI at or above their region-specific baseline levels. 12 states experienced high ILI activity; six states experienced moderate ILI activity; nine states experienced low ILI activity; New York City, Puerto Rico, and 23 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
- Geographic Spread of Influenza: The geographic spread of influenza in 36 states was reported as widespread; Guam, Puerto Rico and 10 states reported regional activity; the District of Columbia and two states reported local activity; two states reported sporadic activity; and the U.S. Virgin Islands reported no activity.