National report: During week 49 (December 2-8, 2001), 11 specimens tested by the World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories across the United States were positive for influenza. Since September 30, a total of 12,282 specimens for influenza viruses have been tested and 172 (1.4%) were positive. Of the 172 isolates identified, 163 (95%) were influenza A viruses and 9 were influenza B viruses. One hundred and twelve (69%) of the influenza A viruses were subtyped, 111 were influenza A (H3N2) and one was an influenza A (H1N1) virus. Eighty-eight (51%) of the influenza A isolates were isolated in Alaska. Influenza A has also been identified in Alabama, Arizona, Colorado, Florida, Hawaii, Kansas, Kentucky, Louisiana, Minnesota, New York, North Carolina, North Dakota, Oregon, Pennsylvania, South Carolina, Texas, Utah, Virginia, Washington West Virginia and Wisconsin. The influenza B isolates were identified in Florida, Hawaii, Louisiana, Michigan, Texas and Virginia.  The proportion of patient visits to sentinel physicians for influenza-like illness (ILI) overall was 1.2%, which is less than the national baseline of 1.9%. The proportion of deaths attributed to pneumonia and influenza as reported by the vital statistics offices of 122 U.S. cities was 6.7% during week 49. This percentage is below the epidemic threshold of 7.6% for this time. Influenza activity was reported as widespread in Alaska and regional in Colorado this week. Sporadic activity was reported from 33 states. No influenza activity was reported from Arkansas, Idaho, Indiana, Massachusetts, Mississippi, New Hampshire, New Jersey, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Dakota, Washington and Wisconsin. Louisiana did not report.