Weekly U.S. Influenza Surveillance Report
CDC's Influenza Division produces a weekly influenza surveillance report, FluView. According to this week's report (March 25 - 31), seasonal influenza activity decreased in the United States. Two states (Alaska and Virginia) experienced high Influenza Like Illness (ILI) activity levels.
During week 13 (March 25-31, 2018), influenza activity decreased in the United States.
- Viral Surveillance: Overall, influenza A(H3) viruses have predominated this season. Since early March, influenza B viruses have been more frequently reported than influenza A viruses. The percentage of respiratory specimens testing positive for influenza in clinical laboratories remains elevated.
- 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 of 99.9 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 2.4%, which is above the national baseline of 2.2%. Seven of 10 regions reported ILI at or above region-specific baseline levels. Two states experienced high ILI activity; eight states experienced moderate ILI activity; New York City and 12 states experienced low ILI activity; and the District of Columbia, Puerto Rico, and 28 states experienced minimal ILI activity.
- Geographic Spread of Influenza: The geographic spread of influenza in 11 states was reported as widespread; Guam, Puerto Rico and 26 states reported regional activity; the District of Columbia and 10 states reported local activity; and the U.S. Virgin Islands and three states reported sporadic activity.