Weekly U.S. Influenza Surveillance Report
CDC's Influenza Division produces a weekly influenza surveillance report, FluView. According to this week's report (March 11-17), seasonal influenza activity decreased in the United States. Six states experienced high Influenza Like Illness (ILI) activity levels.
2017-2018 Influenza Season Week 11 ending March 17, 2018
All data are preliminary and may change as more reports are received.
During week 11 (March 11-17, 2018), influenza activity decreased in the United States.
- Viral Surveillance: Overall, influenza A(H3) viruses have predominated this season. However, in recent weeks the proportion of influenza A viruses has declined, and during week 11, influenza B viruses were more frequently reported than influenza A viruses. 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: Five influenza-associated pediatric deaths were reported.
- Influenza-associated Hospitalizations: A cumulative rate of 93.5 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 2.7%, which is above the national baseline of 2.2%. Nine of 10 regions reported ILI at or above region-specific baseline levels. Six states experienced high ILI activity; nine states experienced moderate ILI activity; New York City, Puerto Rico, the District of Columbia, and 17 states experienced low ILI activity; and 18 states experienced minimal ILI activity.
- Geographic Spread of Influenza: The geographic spread of influenza in 17 states was reported as widespread; Guam, Puerto Rico and 26 states reported regional activity; the District of Columbia and five states reported local activity; and the U.S. Virgin Islands and two states reported sporadic activity.