Weekly U.S. Influenza Surveillance Report
Full report also available as PDF
2016-2017 Influenza Season Week 15 ending April 15, 2017
All data are preliminary and may change as more reports are received.
During week 15 (April 9-15, 2017), influenza activity decreased in the United States.
- Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 15 was influenza B. 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 below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
- Influenza-associated Pediatric Deaths: Five influenza-associated pediatric deaths were reported.
- Influenza-associated Hospitalizations: A cumulative rate for the season of 60.9 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 2.0%, which is below the national baseline of 2.2%. Three of ten regions reported ILI at or above their region-specific baseline levels. Two states experienced moderate ILI activity; New York City and three states experienced low ILI activity; Puerto Rico and 45 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
- Geographic Spread of Influenza: The geographic spread of influenza in 10 states was reported as widespread; Guam, Puerto Rico, and 15 states reported regional activity; the District of Columbia and 19 states reported local activity; six states reported sporadic activity; and the U.S. Virgin Islands reported no activity.