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

Synopsis: During week 52 (December 26, 2015-January 2, 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 52 was influenza A, with influenza A (H1N1)pdm09 viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.

• Novel Influenza A Virus: One human infection with a novel influenza A virus was reported.

• 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: Two influenza-associated pediatric deaths were reported.

• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 2.8%, which is above the national baseline of 2.1%. Seven of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and two states experienced high ILI activity; New York City and two states experienced moderate ILI activity; seven states experienced low ILI activity; 39 states experienced minimal ILI activity; and the District of Columbia had insufficient data.

• Geographic Spread of Influenza: The geographic spread of influenza in Guam and two states were reported as widespread; six states reported regional activity; 13 states reported local activity; the U.S. Virgin Islands and 27 states reported sporadic activity; the District of Columbia and two states reported no influenza activity; and Puerto Rico did not report.

External_F1552.pdf

Stephen B. Thacker CDC Library collection

United States