National Center for Immunization and Respiratory Diseases (U.S.). Influenza Division.

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

Synopsis: During week 47 (November 22-28, 2015), influenza activity increased slightly in the

United States but remained low overall.

• Viral Surveillance: The most frequently identified influenza virus type reported by public health laboratories during week 47 was influenza A viruses, with influenza A (H3) viruses predominating. The percentage of respiratory specimens testing positive for influenza in clinical laboratories was low.

• 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.

• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.9%, which is below the national baseline of 2.1%. Three of 10 regions reported ILI at or above region-specific baseline levels. Puerto Rico and two states experienced moderate ILI activity; four states experienced low ILI activity; New York City and 44 states experienced minimal ILI activity; and the District of Columbia had insufficient data.

• Geographic Spread of Influenza: The geographic spread of influenza in Guam was reported as widespread; Puerto Rico reported regional activity; seven states reported local activity; the District of Columbia, the U.S. Virgin Islands, and 38 states reported sporadic activity; and five states reported no influenza activity.

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