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 48 (November 27-December 3, 2011), influenza activity remained low in the United States.

• U.S. Virologic Surveillance: Of the 2,233 specimens tested by U.S. World Health

• Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division, 37 (1.7%) were positive for influenza.

• Novel influenza A Virus: Two human infections with a novel influenza A virus were

• identified.

• Pneumonia and Influenza (P&I) Mortality Surveillance: The proportion of deaths

• attributed to P&I was below the epidemic threshold.

• Influenza-associated Pediatric Mortality: Two influenza-associated pediatric deaths were reported. These deaths occurred during the 2010-11 influenza season.

• Outpatient Illness Surveillance: The proportion of outpatient visits for influenza-like illness (ILI) was 1.2%, which is below the national baseline of 2.4%. All 10 regions reported ILI below region-specific baseline levels. Two states and New York City experienced low ILI activity, forty-eight states experienced minimal ILI activity, and the District of Columbia had insufficient data.

• Geographic Spread of Influenza: The geographic spread of influenza in one state was reported as local; the District of Columbia, Guam, Puerto Rico, and 30 states reported sporadic activity, and the U.S. Virgin Islands and 19 states reported no influenza activity.

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