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 7, 2006-Week 1

Error processing SSI file

Synopsis:

During week 1 (January 1 - January 7, 2006)*, influenza activity continued approximately at the same level as recent weeks in the United States. Two hundred three (9.1%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories were positive for influenza. The proportion of patient visits to sentinel providers for influenza-like illness (ILI) was above the national baseline. The proportion of deaths attributed to pneumonia and influenza was below the baseline level. Seven states reported widespread influenza activity; 11 states reported regional influenza activity; 9 states reported local influenza activity; 21 states, New York City, the District of Columbia, and Puerto Rico reported sporadic influenza activity; and 2 states reported no influenza activity.

Laboratory Surveillance*:

During week 1, WHO and NREVSS laboratories reported 2,223 specimens tested for influenza viruses and 203 (9.1%) were positive. Of these, 90 were influenza A (H3N2) viruses, 105 were influenza A viruses that were not subtyped, and 8 were influenza B viruses.

Since October 2, 2005, WHO and NREVSS laboratories have tested a total of 38,932 specimens for influenza viruses and 1,557 (4.0%) were positive. Among the 1,557 influenza viruses, 1,499 (96.3%) were influenza A viruses and 58 (3.7%) were influenza B viruses. Seven hundred sixty-five (51.0%) of the 1,499 influenza A viruses have been subtyped: 760 (99.3%) were influenza A (H3N2) viruses and 5 (0.7%) were influenza A (H1N1) viruses. Forty-six states from all surveillance regions** have reported laboratory-confirmed influenza this season. Five hundred eighty (37.3%) of the 1,557 isolates have been reported by the Mountain region and 332 (21.3%) have been reported by the Pacific region.

INFLUENZA Virus Isolated

View Chart Data | View Full Screen

Antigenic Characterization:

CDC has antigenically characterized 73 influenza viruses [65 influenza A (H3N2), 1 influenza A (H1), and 7 influenza B viruses] collected by U.S. laboratories since October 1, 2005. Of the 65 influenza A (H3N2) viruses, 54 were characterized as A/California/07/2004-like, which is the influenza A (H3N2) component recommended for the 2005-06 influenza vaccine, and 11 showed reduced titers with antisera produced against A/California/07/2004. The hemagglutinin protein of the influenza A (H1) virus was similar antigenically to the hemagglutinin of the vaccine strain A/New Caledonia/20/99. Influenza B viruses currently circulating can be divided into two antigenically distinct lineages represented by B/Yamagata/16/88 and B/Victoria/2/87 viruses. Five of the influenza B viruses isolated belong to the B/Yamagata lineage. One was similar to B/Shanghai/361/2002, the recommended influenza B component for the 2005-06 influenza vaccine, and 4 were characterized as B/Florida/07/2004-like. B/Florida/07/2004 is a minor antigenic variant of B/Shanghai/361/2002. Two influenza B viruses were identified as belonging to the B/Victoria lineage.

Pneumonia and Influenza (P&I) Mortality Surveillance*:

During week 1, 7.3% of all deaths reported by the vital statistics offices of 122 U.S. cities were reported as due to pneumonia or influenza. This percentage is below the epidemic threshold of 8.0% for week 1.

Pneumonia And Influenza Mortality

View Full Screen

Influenza-Associated Pediatric Mortality*:

One influenza-associated pediatric death was reported for week 1. Since October 2, 2005, CDC has received reports of six influenza-associated pediatric deaths, four of which occurred during the current influenza season.

Influenza-Associated Pediatric Hospitalizations*:

Laboratory-confirmed influenza-associated pediatric hospitalizations are monitored in two population-based surveillance networks†: the Emerging Infections Program (EIP) and the New Vaccine Surveillance Network (NVSN). During October 1 - December 24, 2005, the preliminary influenza-associated hospitalization rate for children 0-4 years old reported by the EIP was 0.17 per 10,000. The EIP also monitors hospitalizations in children 5-17 years old. The preliminary influenza-associated hospitalization rate for this age group reported by EIP was 0.01 per 10,000. The overall hospitalization rate reported by the EIP for children aged 0-17 years was 0.06 per 10,000. During October 30 - December 24, 2005, there were no laboratory-confirmed influenza-associated hospitalizations for children 0-4 years old in the NVSN. EIP and NVSN hospitalization rate estimates are preliminary and may change as data continue to be collected.

NVSN laboratory-confirmed influenza-associated hospitalizations for children 0-4 years old
View Full Screen

Influenza-like Illness Surveillance*:

During week 1, 2.7%*** of patient visits to U.S. sentinel providers were due to ILI. This percentage is above the national baseline of 2.2%. The percentage of visits for ILI ranged from 1.5% in the New England region to 5.5% in the West South Central 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*:

During week 1, 7 states (Arizona, California, Colorado, Nevada, New Mexico, Oregon, and Texas) reported widespread influenza activity. Eleven states (Alaska, Connecticut, Idaho, Iowa, Kansas, Mississippi, Pennsylvania, Tennessee, Utah, Washington, and Wyoming) reported regional influenza activity. Nine states (Georgia, Indiana, Kentucky, Massachusetts, Montana, Nebraska, Ohio, Oklahoma, and Virginia) reported local influenza activity. Twenty-one states (Alabama, Arkansas, Delaware, Florida, Hawaii, Illinois, Maine, Maryland, Michigan, Minnesota, Missouri, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Rhode Island, South Carolina, South Dakota, West Virginia, and Wisconsin), New York City, the District of Columbia, and Puerto Rico reported sporadic influenza activity. Two states reported no influenza activity.

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

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

 

Foot notes

Report prepared January 13, 2006

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