National report: During week 45 (November 4-10, 2001), two 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 4,891 specimens for influenza viruses have been tested and 39 (1%) were positive. Of the 39 isolates identified, 38 were influenza A viruses and 1 was an influenza B virus. Fourteen of the influenza A viruses were subtyped, all were influenza A (H3N2). Influenza A isolates have been identified in Alaska, Arizona, Florida, Kentucky, Louisiana, New York, Texas and Utah. The influenza B isolate was identified in Texas.  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 45. This percentage is below the epidemic threshold of 7.2% for this time. Twenty-two state and territorial health departments (Colorado, Florida, Georgia, Indiana, Kansas, Kentucky, Louisiana, Maine, Michigan, Missouri, Nebraska, Nevada, New Mexico, New York, North Dakota, Ohio, Pennsylvania, Tennessee, Texas, Utah, West Virginia, and Wyoming) reported sporadic influenza activity and 26 reported no influenza activity.