Weekly U.S. Influenza Surveillance Report
CDC’s Influenza Division collects, compiles, and analyzes information on influenza activity year-round in the U.S. and produces FluView, a weekly influenza surveillance report. During week 13, ending April 1, influenza activity decreased in the United States, however, widespread influenza activity was still reported by Puerto Rico and 24 states.
2016-2017 Influenza Season Week 13 ending April 1, 2017
All data are preliminary and may change as more reports are received.
During week 13 (March 26-April 1, 2017), influenza activity decreased but remained elevated in the United States.
- Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 13 was influenza B. The percentage of respiratory specimens testing positive for influenza in clinical laboratories decreased slightly.
- 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: Seven influenza-associated pediatric deaths were reported.
- Influenza-associated Hospitalizations: A cumulative rate for the season of 57.2 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 2.9%, which is above the national baseline of 2.2%. Six of ten regions reported ILI at or above their region-specific baseline levels. Nine states experienced high ILI activity; five states experienced moderate ILI activity; New York City and nine states experienced low ILI activity; Puerto Rico and 27 states experienced minimal ILI activity; and the District of Columbia had insufficient data.
- Geographic Spread of Influenza: The geographic spread of influenza in 24 states was reported as widespread; Guam, Puerto Rico and 19 states reported regional activity; the District of Columbia and five states reported local activity; two states reported sporadic activity; and the U.S. Virgin Islands reported no activity.