Update: Influenza Activity --- United States, 2003--04 Season

CDC surveillance indicates that influenza activity in the United States was earlier than usual during the 2003–2004 season, beginning in October 2003, peaking during late November–December, and declining rapidly during January–February 2004. As of March 27, CDC had received reports of 142 influenza-associated deaths in children aged <18 years. Since early February, avian influenza outbreaks in poultry have been reported from multiple locations in North America. No confirmed cases of human infection with avian influenza viruses have occurred in the United States, although two have occurred in Canada.

Update: Influenza Activity --- United States, January 18--24, 2004

Describes influenza activity in the United States during January 18–24, 2004, identifying states reporting widespread, regional, local, and sporadic activity as well as influenza-associated deaths among children aged <18 years. The number of states reporting widespread influenza activity decreased from five to one, and the percentage of outpatient visits for influenza-like illness remained at 2.0%, which is below the national baseline of 2.5%; the percentage of deaths attributed to pneumonia and influenza was 9.7%. As of January 26, 2004, CDC had received reports of 121 laboratory-confirmed influenza-associated deaths among children aged <18 years. All influenza-associated deaths among children aged <18 years should be reported to CDC through state and local health departments during the 2003–04 season.

Update: Influenza Activity --- United States, January 11--17, 2004

Describes influenza activity in the United States during January 11–17, 2004, identifying states reporting widespread, regional, local, and sporadic activity as well as influenza-associated deaths among children <18 years. The number of states reporting widespread influenza activity decreased from 20 to five, and the percentage of outpatient visits for influenza-like illness declined below the national baseline of 2.5% for the first time since the reporting week ending November 8, 2003; the percentage of deaths attributed to pneumonia and influenza was unchanged. Since October 2003, CDC has received reports from 33 states of 111 laboratory-confirmed influenza-associated deaths among children aged <18 years. All influenza-associated deaths among children aged <18 years should be reported to CDC through state and local health departments during the 2003–04 season.

Preliminary Assessment of the Effectiveness of the 2003--04 Inactivated Influenza Vaccine --- Colorado, December 2003

Describes a retrospective cohort study conducted among workers at a Colorado hospital to provide preliminary data on the effectiveness of trivalent inactivated influenza vaccine (TIV) against influenza-like illness (ILI). TIV had no or low effectiveness against ILI. This study does not provide data that would permit an assessment of the effectiveness of TIV against laboratory-confirmed influenza and its complications. Additional studies to provide such data are under way. Because TIV was effective against laboratory-confirmed influenza and influenza-related complications in previous years in which it was not effective against ILI, and because influenza B and influenza A (H1N1) viruses might cause significant illness later this season, influenza vaccine continues to be recommended for persons at increased risk for influenza-related complications, their household contacts, and health-care personnel.

Update: Influenza Activity --- United States, January 4--10, 2004

Describes influenza activity in the United States during January 4–10, 2004, and identifies number of states reporting widespread, regional, local, and sporadic influenza activity. During the reporting week ending January 10, 2004, World Health Organization (WHO) laboratories reported testing 2,670 specimens for influenza viruses. Of the 319 (11.9%) that were positive, 52 were influenza A (H3N2) viruses, 261 were influenza A viruses that were not subtyped, and six were influenza B viruses. The percentage of outpatient visits for influenza-like illness continue to decrease in all nine surveillance regions during the week ending January 10.

Update: Influenza Activity --- United States, December 21, 2003--January 3, 2004

Describes influenza activity in the United States during December 21, 2003–January 3, 3004, and identifies number of states reporting widespread, regional, local, and sporadic influenza activity. During the reporting week ending January 3, 2004, World Health Organization (WHO) laboratories reported testing 3,092 specimens for influenza viruses. Of the 641 (20.7%) that were positive, 111 were influenza A (H3N2) viruses, 524 were influenza A viruses that were not subtyped, and six were influenza B viruses. The percentage of outpatient visits for influenza-like illness decreased in all nine surveillance regions during the week ending January 3, with an overall national percentage of 6.2%.

Update: Influenza-Associated Deaths Reported Among Children Aged <18 Years --- United States, 2003--04 Influenza Season

Describes deaths among children with evidence of influenza virus infection based on data reported as of January 2, 2004. Since October 2003, CDC has received reports of 93 influenza-associated deaths among children aged <18 years. All patients had evidence of influenza virus infection detected by rapid antigen testing or other laboratory tests. All influenza-associated deaths among children aged <18 years should be reported to CDC through state and local health departments during the 2003–04 season.

Update: Influenza Activity --- United States, December 14--20, 2003

Describes influenza activity in the United States during December 14–20, 2003, and identifies number of states reporting widespread, regional, local, and sporadic influenza activity. During the reporting week, World Health Organization laboratories reported testing 3,693 specimens for influenza viruses. A total of 1,297 (35.1%) were positive; 323 were influenza A (H3N2) viruses, 964 were influenza A viruses that were not subtyped, and 10 were influenza B viruses. Because data from the National Respiratory and Enteric Virus Surveillance System laboratories for the week ending December 20 were not available at the time of this report, numbers might change substantially next week.

Update: Influenza-Associated Deaths Reported Among Children Aged <18 Years --- United States, 2003--04 Influenza Season

Since October, 42 influenza-associated deaths among children aged <18 years have been reported to CDC. The median age of these patients was 4 years (range: 9 weeks–17 years). Seventeen of the children had underlying chronic medical conditions, and five with no previous medical conditions had invasive bacterial co-infections. To improve surveillance, CDC has requested that all influenza-associated deaths of children aged <18 years be reported through state health departments to CDC. Forms will be available on the Epidemic Information Exchange.

Update: Influenza Activity --- United States, December 7--13, 2003

Update: Influenza Activity --- United States,
2003--04 Season

Using Live, Attenuated Influenza Vaccine for Prevention and Control of Influenza

Prevention and Control of Influenza: Recommendations of the Advisory Committee on Immunization Practices (ACIP)