All data are preliminary and may change as more reports are received.

Synopsis: During week 3 (January 17-23, 2016), influenza activity increased slightly in the United States.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 3 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories increased.

• Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below their system-specific epidemic threshold in both the NCHS Mortality Surveillance System and the 122 Cities Mortality Reporting System.

• Influenza-associated Pediatric Deaths: No influenza-associated pediatric deaths were reported.

• Influenza-associated Hospitalizations: A cumulative rate for the season of 2.1 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 2.2%, which is above the national baseline of 2.1%. Six of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico experienced high ILI activity; three states experienced moderate ILI activity; five states experienced low ILI activity; New York City and 42 states experienced minimal ILI activity; and the District of Columbia had insufficient data.

• Geographic Spread of Influenza: The geographic spread of influenza in four states was reported as widespread; Puerto Rico and 14 states reported regional activity; Guam and 12 states reported local activity; and the District of Columbia, the U.S. Virgin Islands and 20 states reported sporadic activity.

External_F1603.pdf

Stephen B. Thacker CDC Library collection

United States