Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file

Weekly Report: Influenza Summary Update

Week ending January 31, 2004-Week 4

Error processing SSI file

The following information may be quoted:

Synopsis:

Influenza activity remained low during the week of January 25-31, 2004. The percentage of patient visits for influenza-like illness (ILI) remained below the national baseline of 2,5 % for the third consecutive week. Mortality due to pneumonia and influenza (9,3 %) continued to decline, but remained above the epidemic threshold during week 4 (8,2 %). Seventy-six (6,3 %) of 1 213 specimens collected from throughout the United States and tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories were positive for influenza. There were no reports of widespread influenza activity from state and territorial epidemiologists during week 4. Eleven states reported regional activity, 20 states and New York City reported local activity, 18 states and the District of Columbia reported sporadic activity, and one state reported no activity. Reports of influenza-associated deaths in children continue to be collected from state health departments.

Laboratory Surveillance*:

During week 4, WHO and NREVSS laboratories reported 1 213 specimens tested for influenza viruses, and 76 (6,3 %) were positive. Of these, 49 were influenza A (H3N2) viruses, 26 were influenza A viruses that were not subtyped, and 1 was an influenza B virus.

Since September 28, WHO and NREVSS laboratories have tested 87 333 specimens for influenza viruses, of which 22 199 (25,4 %) were positive. Of these, 22 067 (99,4 %) were influenza A viruses, and 132 (0,6 %) were influenza B viruses. Of the 22 067 influenza A viruses, 5 781 (26,2 %) have been subtyped; 5 780 (99,9 %) were influenza A (H3N2) viruses and one (0,1 %) was an influenza A (H1) virus.

Influenza Virus Isolated


View Chart Data

Antigenic Characterization:

CDC has antigenically characterized 592 influenza viruses collected by U.S. laboratories since October 1: two influenza A (H1) viruses, 584 influenza A (H3N2) viruses, and six influenza B viruses. The hemagglutinin proteins of the influenza A (H1) viruses were similar antigenically to the hemagglutinin of the vaccine strain A/New Caledonia/20/99. Of the 584 influenza A (H3N2) isolates that have been characterized, 106 (18,2 %) were similar antigenically to the vaccine strain A/Panama/2007/99 (H3N2), and 478 (81,8 %) were similar to the drift variant, A/Fujian/411/2002 (H3N2). Five influenza B viruses characterized were similar antigenically to B/Sichuan/379/99 and 1 was similar antigenically to B/Hong Kong/330/2001.

Pneumonia and Influenza (P&I) Mortality Surveillance:

During week 4, 9,3 % of all deaths reported by the vital statistics offices of 122 U.S. cities were due to pneumonia and influenza. This percentage is above the epidemic threshold of 8,2 % for week 4.

Pneumonia And Influenza Mortality

View Full Screen

Influenza-like Illness Surveillance *:

The percentage of patient visits to approximately 1 000 U.S. sentinel providers nationwide for ILI was 1,9 %** during week 4, which is below the national baseline of 2,5 %. The percentage of patient visits for ILI in all nine surveillance regions*** ranged from 3,5 % in the West South Central region to 0,9 % in the New England region. Due to wide variability in regional level data, it is not appropriate to apply the national baseline to regional level data.

Bar Chart for Influenza-like Illness
View Chart Data | View Full Screen

Influenza Activity as Assessed by State and Territorial Epidemiologists**:

There were no reports of widespread activity for week 4. Regional activity was reported in 11 states (Connecticut, Florida, Kentucky, Massachusetts, Mississippi, Montana, New Jersey, New York, Ohio, South Carolina, and Wyoming). Local activity was reported in 20 states (California, Colorado, Delaware, Hawaii, Indiana, Iowa, Louisiana, Maine, Maryland, Michigan, Minnesota, Missouri, Nebraska, North Carolina, Pennsylvania, Rhode Island, Vermont, Virginia, West Virginia, and Wisconsin) and New York City. Sporadic activity was reported in 18 states (Alaska, Arizona, Arkansas, Georgia, Idaho, Illinois, Kansas, Nevada, New Hampshire, New Mexico, North Dakota, Oklahoma, Oregon, South Dakota, Tennessee, Texas, Utah, and Washington) and the District of Columbia. Alabama reported no activity. <

Influenza-associated deaths in children aged <18 years:

As of February 5, CDC had received reports of 129 influenza-associated deaths in U.S. residents aged <18 years. These data are preliminary and subject to change as more data become available. All patients had evidence of influenza virus infection detected by rapid-antigen testing or other laboratory tests. Among reported deaths, 64 (50 %) were male; the gender for one child was not reported. The median age was 3.4 years (range: 2 weeks--17 years). Of the 78 children aged <5 years, 37 were aged 6--23 months. Thirty-two children had medical conditions that put them at increased risk for complications from influenza. Of the children whose influenza vaccination status was reported, 3 were vaccinated according to current recommendations (1), and 75 were not vaccinated.

U. S. map for Weekly Influenza Activity
View Full Screen

--------------------------------------------------------------------------------

* Reporting is incomplete for this week. Numbers may change as more reports are received.

** The national and regional percentage of patient visits for ILI is weighted on the basis of state population.

*** Surveillance Regions: New England (Connecticut, Maine, Massachusetts, New Hampshire, Vermont, Rhode Island); Mid-Atlantic (New Jersey, New York City, Pennsylvania, Upstate New York); East North Central (Illinois, Indiana, Michigan, Ohio, Wisconsin); West North Central (Iowa, Kansas, Minnesota, Missouri, Nebraska, North Dakota, South Dakota); South Atlantic (Delaware, Florida, Georgia, Maryland, North Carolina, South Carolina, Virginia, Washington, D.C., West Virginia); East South Central (Alabama, Kentucky, Mississippi, Tennessee); West South Central (Arkansas, Louisiana, Oklahoma, Texas); Mountain (Arizona, Colorado, Idaho, Montana, Nevada, New Mexico, Utah, Wyoming); Pacific (Alaska, California, Hawaii, Oregon, Washington)

1. CDC. Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2003;52(No. RR-8).

Report prepared January 31, 2004

Error processing SSI file
Error processing SSI file
Error processing SSI file
Error processing SSI file