Adult groups included in the 2008 Advisory Committee on Immunization Practices (ACIP) recommendation for annual influenza vaccination include all persons aged >50 years, women who will be pregnant during the influenza season, persons aged 18–49 years with high-risk conditions, and other persons at increased risk for complications from influenza. Health-care personnel and household contacts and caregivers of persons at high risk also should receive annual influenza vaccination, as should adults who want to reduce their risk for becoming ill with influenza or for transmitting it to others.

Children aged <5 years have more influenza-related medical-care visits compared with older children, and those aged <2 years are at the greatest risk for influenza-related hospitalizations. This report, based on data from the 2007 National Immunization Survey (NIS), provides an assessment of influenza vaccination coverage among children aged 6–23 months during September–December of the 2006–07 influenza season.

Influenza vaccination coverage among children historically has been low. The results of this report highlights the need to identify barriers to influenza vaccination and to develop more effective interventions to promote vaccination of children aged 6–59 months who are at high risk for influenza-related morbidity and mortality.

During May 18–September 19, 2008, influenza A (H1), influenza A (H3), and influenza B viruses were detected worldwide and were identified sporadically in the United States. This report summarizes influenza activity in the United States and worldwide since the last update and reviews the new influenza vaccine recommendations for the upcoming season.

This report updates the 2007 recommendations by CDC's Advisory Committee on Immunization Practices (ACIP) regarding the use of influenza vaccine and antiviral agents. The 2008 recommendations include new and updated information, including a new recommendation that annual vaccination be administered to all children aged 5–18 years, beginning in the 2008–09 influenza season, if feasible, but no later than the 2009–10 influenza season.

During the 2007–08 influenza season, influenza activity peaked in mid-February in the United States and was associated with greater mortality and higher rates of hospitalization of children aged 0–4 years, compared with each of the previous three seasons. This report summarizes influenza activity in the United States and worldwide during the 2007–08 influenza season (September 30, 2007–May 17, 2008).

During 2006, approximately 6.8 million (9.3%) U.S. children and 16.1 million (7.3%) U.S. adults were reported to have asthma. This report provides the first examination of influenza vaccination rates and related factors across a national sample of persons with asthma aged >2 years.

This report summarizes U.S. influenza activity since September 30, 2007, the start of the 2007--08 influenza season, and updates the previous summary. Low levels of influenza activity were reported from October through early December. Activity increased from mid-December and peaked in mid-February.

During clinical trials, the efficacy of vaccination with inactivated influenza vaccines for the prevention of serologically confirmed influenza infection has been estimated as high as 70%--90% among healthier adults. However, the effectiveness of annual influenza vaccination typically is lower during those influenza seasons when a suboptimal match between the vaccine strains and circulating influenza strains is observed.

From September through early December, influenza activity remained low in the United States. This report summarizes U.S. influenza activity since the beginning of the 2007--08 influenza season and updates the previous summary.

This report summarizes U.S. influenza activity since September 30, 2007, the beginning of the 2007--08 influenza season, and updates the previous summary. During September through early December, influenza activity remained low in the United States. Activity increased from early December through the end of the year and has continued to increase in January and February.

This report describes the results of a survey of primary-care physicians (PCPs), which indicated that 69.0% of the PCPs administered influenza tests to patients who had influenza-like symptoms during the influenza season and that 53.8% prescribed antiviral agents, including two (i.e., amantadine and rimantadine) no longer recommended by CDC. This report emphasizes the need for health agencies, medical societies, and continuing medical education organizations to provide advanced educational programs for physicians that increase awareness of recommendations regarding appropriate influenza testing and use of antiviral agents.

During September 30--December 1, 2007, influenza activity remained low in the United States. This report summarizes U.S. influenza activity since September 30, the start of the 2007--08 influenza season.

During May 20--September 15, 2007, influenza A (H1), influenza A (H3), and influenza B viruses cocirculated worldwide and were identified sporadically in the United States. This report summarizes influenza activity in the United States and worldwide.

Comprehensive measures are needed to improve influenza vaccination coverage among adults aged >18 years in the United States. This report describes strategies to increase adoption of recommended adult immunization practices by health-care providers, raise public awareness concerning influenza vaccination, vaccinate throughout the influenza season, and ensure stable supplies of readily available vaccine.

Children aged <2 years are at increased risk for influenza-related hospitalizations. Results from the 2006 National Immunization Survey underscore the need to continue to monitor influenza vaccination coverage among young children, develop systems to provide childhood influenza vaccination services more efficiently, and increase awareness among health-care providers and caregivers concerning the effectiveness of influenza vaccination among young children

In 2006, the Advisory Committee on Immunization Practices expanded its 2004 recommendation for routine influenza vaccination of children aged 6--23 months to include children aged 24--59 months. This report discusses CDC’s findings that in six immunization sentinel sites, <30% of children aged 6--23 months and <20% of children aged 24--59 months were fully vaccinated.

During the 2006--07 season, influenza activity peaked in mid-February in the United States and was associated with less mortality and lower rates of pediatric hospitalizations than during the previous three seasons. This report summarizes influenza activity in the United States and worldwide during the 2006--07 influenza season (October 1, 2006--May 19, 2007) and describes the composition of the 2007--08 influenza vaccine.

Estimated vaccination coverage remains <50% among certain groups for whom routine annual vaccination is recommended, including young children and adults with risk factors for influenza complications, health-care personnel, and pregnant women. This report updates the 2006 recommendations by CDC's ACIP regarding the use of influenza vaccine and antiviral agents.

Children with asthma are at high risk for complications from influenza, and influenza vaccination has been determined to safely and effectively reduce rates of influenza in these children. This report underscores the need to increase influenza vaccination coverage in children with asthma aged 2--17 years by identifying and overcoming barriers to vaccination.

Low levels of influenza activity were reported from October through early December. This report summarizes U.S. influenza activity since the beginning of the 2006--07 influenza season and updates the previous summary.

During October 1--December 9, 2006, influenza activity remained low in the United States overall but increased in southeastern states. This report summarizes U.S. influenza activity since October 1, the beginning of the 2006--07 influenza season, and updates the previous summary.

This report assesses influenza vaccination coverage among children aged 6–23 months during the 2005–06 influenza season by using data from six immunization information system sentinel sites. Vaccination coverage with 1 or more doses varied widely among sites, with coverage increasing from the preceding influenza season in four sites. However, less than 23% of children in five sites were fully vaccinated, underscoring the need for increased measures to improve the proportion of children who are fully vaccinated.

This report provides an assessment of influenza vaccination coverage among children aged 6--23 months during the 2004--05 influenza season. Coverage in that age group nearly doubled from the 2003--04 influenza season, with substantial variability among states and urban areas. However, the percentage of fully vaccinated children remained low, underscoring the need for improved pediatric vaccination coverage and ongoing monitoring of coverage among young children and their close contacts.

Vaccination of persons at increased risk for complications from influenza and pneumococcal disease is a key public health strategy in the United States. One of the Healthy People 2010 objectives is to achieve 90% coverage of noninstitutionalized adults aged >65 years for both influenza and pneumococcal vaccinations. To assess progress toward this goal, this report examines vaccination coverage for persons interviewed in the 2004 and 2005 Behavioral Risk Factor Surveillance System surveys.

Updates the 2005 recommendations by the Advisory Committee on Immunization Practices (ACIP) regarding the use of influenza vaccine and antiviral agents. The 2006 recommendations include new and updated information. Principal changes include 1) recommending vaccination of children aged 24--59 months and their household contacts and out-of-home caregivers against influenza; 2) highlighting the importance of administering 2 doses of influenza vaccine for children aged 6 months--<9 years who were previously unvaccinated; 3) advising health-care providers, those planning organized campaigns, and state and local public health agencies to a) develop plans for expanding outreach and infrastructure to vaccinate more persons than the previous year and b) develop contingency plans for the timing and prioritization of administering influenza vaccine, if the supply of vaccine is delayed and/or reduced; 4) reminding providers that they should routinely offer influenza vaccine to patients throughout the influenza season; 5) recommending that neither amantadine nor rimantadine be used for the treatment or chemoprophylaxis of influenza A in the United States until evidence of susceptibility to these antiviral medications has been re-established among circulating influenza A viruses; and 6) using the 2006--07 trivalent influenza vaccine virus strains.

Describes U.S. and worldwide influenza activity during the 2005--2006 influenza season and composition of the 2006--07 influenza vaccine and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The weekly percentage of patient visits to U.S. influenza sentinel providers for ILI first exceeded the national baseline of 2.2% during the weeks ending December 17, 2005--April 1, 2006 and peaked twice, once at 3.3% for the week ending December 31, 2005, and again at 3.2% for the week ending March 4, 2006.The percentage of deaths in the United States attributed to pneumonia and influenza did not exceed the epidemic threshold but peaked twice at 7.8%, during the weeks ending January 14, 2006, and March 18, 2006. During January 2004--June 13, 2006, a total of 225 human cases of avian influenza A (H5N1) infection resulting in 128 deaths were reported to WHO.

Describes influenza activity in the United States during April 2--8, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity decreased to 10, and the percentage of outpatient visits for influenza-like illness was 1.9%, which was below the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.4%, which was below the epidemic threshold of 8.0%. From December 2003 through April 13, 2006, a total of 194 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 109 deaths, were reported to WHO.

Describes influenza activity in the United States during March 26--April 1, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity decreased to 13, and the percentage of outpatient visits for influenza-like illness was 2.6%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.6%, which was below the epidemic threshold of 8.1%. From December 2003 through April 11, 2006, a total of 193 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 109 deaths, were reported to WHO.

Describes influenza activity in the United States during March 19--25, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity decreased to 16, and the percentage of outpatient visits for influenza-like illness was 2.5%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.7%, which was below the epidemic threshold of 8.2%. From December 2003 through April 4, 2006, a total of 191 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 108 deaths, were reported to WHO.

Describes influenza activity in the United States during March 5–March 11, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity remained at 25, and the percentage of outpatient visits for influenza-like illness was 3.0%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.6%, which was below the epidemic threshold of 8.3%. From December 2003 through March 13, 2006, a total of 184 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 103 deaths, were reported to WHO.

Describes influenza activity in the United States during March 12--March 18, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity decreased to 23, and the percentage of outpatient visits for influenza-like illness was 2.5%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.8%, which was below the epidemic threshold of 8.2%. From December 2003 through March 24, 2006, a total of 186 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 105 deaths, were reported to WHO.

Describes influenza activity in the United States during February 26–March 4, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to 25, and the percentage of outpatient visits for influenza-like illness was 3.0%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.0%, which was below the epidemic threshold of 8.3%. From December 2003 through March 13, 2006, a total of 177 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 98 deaths, were reported to WHO.

Describes influenza activity in the United States during February 19--25, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to 21, and the percentage of outpatient visits for influenza-like illness was 3.4%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.0%, which was below the epidemic threshold of 8.3%. From December 2003 through March 6, 2006, a total of 175 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 95 deaths, were reported to WHO.

Describes influenza activity in the United States during February 5--11, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to 17, and the percentage of outpatient visits for influenza-like illness was 2.8%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.3%, which was below the epidemic threshold of 8.3%. From December 2003 through February 27, 2006, a total of 173 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 93 deaths, were reported to WHO.

Describes influenza activity in the United States during February 5–11, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to 13, and the percentage of outpatient visits for influenza-like illness was 2.5%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.0%, which was below the epidemic threshold of 8.3%. From December 2003 through February 20, 2006, a total of 170 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 92 deaths, were reported to WHO.

Summarizes recommendations of the Healthcare Infection Control Practices Advisory Committee (HICPAC) and the Advisory Committee on Immunization Practices (ACIP) concerning influenza vaccination of health-care personnel (HCP) in the United States. These recommendations apply to HCP in acute care hospitals, nursing homes, skilled nursing facilities, physician's offices, urgent care centers, and outpatient clinics, and to persons who provide home health care and emergency medical services. The recommendations are targeted at health-care facility administrators, infection-control professionals, and occupational health professionals responsible for influenza vaccination programs and influenza infection-control programs in their institutions. HICPAC and ACIP recommend that all HCP be vaccinated annually against influenza. Facilities that employ HCP are strongly encouraged to provide vaccine to their staff by using evidence-based approaches that maximize vaccination rates.

Describes influenza activity in the United States during January 29, 2006--February 4, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to nine, and the percentage of outpatient visits for influenza-like illness was 2.3%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.4%, which was below the epidemic threshold of 8.2%. From December 2003 through February Update: Influenza Activity --- United States and Worldwide, 2005--06 Season, and Composition of the 2006--07 Influenza Vaccine>

(Asian Lineage) Virus Real-Time Reverse Transcription–Polymerase Chain Reaction Primer and Probe Set and inactivated virus as a source of positive RNA control for the in vitro qualitative detection of highly pathogenic influenza A/H5 virus (Asian lineage). The primer and probe set, developed at CDC, detects influenza viruses associated with laboratory-confirmed infections of avian influenza in humans in east Asia, Turkey, and Iraq.

Describes influenza activity in the United States during January 22–28, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity remained at five, and the percentage of outpatient visits for influenza-like illness was 2.4%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.6%, which was below the epidemic threshold of 8.2%. From December 2003 through February 6, 2006, a total of 165 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 88 deaths, were reported to WHO.

Assesses childhood influenza vaccination coverage for the 2003–04 influenza season, the second year the Advisory Committee on Immunization Practices encouraged influenza vaccination of children aged 6–23 months. Data from the 2004 National Immunization Survey indicate that 17.5% of children in that age group received 1 or more doses of influenza vaccine, and 8.4% were fully vaccinated during the 2003–04 influenza season, compared with 7.4% and 4.4% for the 2002–03 season. Substantial variability in influenza vaccination coverage was observed among states and selected urban areas, ranging from 5.7% in Miami-Dade County, Florida, to 47.6 in Rhode Island.

Describes influenza activity in the United States during January 15–21, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity decreased to five, and the percentage of outpatient visits for influenza-like illness was 2.3%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.4%, which was below the epidemic threshold of 8.2%. From December 2003 through January 30, 2006, a total of 160 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 85 deaths, were reported to WHO.

Describes influenza activity in the United States during January 8–14, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to eight, and the percentage of outpatient visits for influenza-like illness was 2.1%, which was below the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.8%, which was below the epidemic threshold of 8.1%. From December 2003 through January 23, 2006, a total of 151 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 82 deaths, were reported to WHO.

Describes influenza activity in the United States during January 1–7, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity remained at seven, and the percentage of outpatient visits for influenza-like illness was 2.7%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.3%, which was below the epidemic threshold of 8.0%. From December 2003 through January 14, 2006, a total of 148 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 79 deaths, were reported to WHO.

Describes new findings regarding the resistance to adamantanes or M2 ion channel inhibitors (i.e., amantadine and rimantadine) of influenza A viruses currently circulating in the United States and provides interim recommendations that these drugs not be used during the remainder of the 2005–06 influenza season. Amantadine also is used to treat symptoms of Parkinson disease and may continue to be used for this indication. During this period, neuraminidase inhibitors (i.e., oseltamivir and zanamivir) should be prescribed if an antiviral medication is indicated for the treatment of influenza, or oseltamivir should be prescribed for chemoprophylaxis of influenza.

Describes influenza activity in the United States during December 25–31, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity increased to seven, and the percentage of outpatient visits for influenza-like illness was 3.3%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 6.8%, which was below the epidemic threshold of 7.9%. From December 2003 through January 10, 2006, a total of 147 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 78 deaths, were reported to WHO.

Describes influenza activity in the United States during December 18–24, 2006, and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The number of states reporting widespread influenza activity was four, and the percentage of outpatient visits for influenza-like illness was 3.1%, which was above the national baseline of 2.2%; the percentage of deaths attributed to pneumonia and influenza was 7.0%, which was below the epidemic threshold of 7.8%. From December 2003 through December 30, 2005, a total of 142 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 74 deaths, were reported to WHO.

Describes influenza vaccination levels for two age groups with increased risk for influenza-related complications. This report analyzed data from the 2003 National Health Interview Survey, which determined that influenza vaccination coverage among persons aged >65 years and persons aged 18–64 years with high-risk conditions was 65.6% and 34.1%, respectively, substantially below the national health objective levels for 2010 of 90% and 60%.

In 2003, the Advisory Committee on Immunization Practices (ACIP) included healthy pregnant women in their second or third trimester of pregnancy among persons at high risk for whom influenza vaccination was indicated. Also included were women at any stage of pregnancy with certain chronic medical conditions. However, only 13% of pregnant women received influenza vaccination in 2003. To assess understanding of the ACIP recommendations among obstetrician-gynecologists, a survey was conducted in May 2004, which indicated that 52% would recommend influenza vaccination for a healthy woman in the first trimester of pregnancy, 95% would recommend the vaccine for a healthy pregnant woman beyond the first trimester, and 63% would recommend vaccination for a woman with a medical condition in the first trimester.
 

To assess influenza vaccination coverage among persons aged 50–64 years for the 2004–05 influenza season relative to the 2003–04 season and to estimate the effect of shortages on selected subgroups, the National Committee for Quality Assurance analyzed data from persons enrolled in commercial managed care health plans. The findings of this analysis indicated that vaccination coverage for the surveyed population decreased from 52.4% to 28.1%, a decrease of approximately 46%.
 

This report updates projections of influenza vaccine supply and previous recommendations for priority use of trivalent inactivated influenza vaccine during the 2005–06 influenza season. However, because of the uncertainties regarding production of influenza vaccine, the exact number of available doses and timing of vaccine distribution for the 2005–06 influenza season remains unknown.
 

Recommendations are offered to mitigate a possible disruption in the supply of inactivated influenza vaccine. Although total vaccine supply for the 2005–06 influenza season is not known, the minimum anticipated supply is approximately 58–60 million doses of inactivated vaccine and 3 million doses of live, attenuated vaccine. This estimated supply is similar to that available during the 2004–05 season and would be adequate to satisfy historical demand for influenza vaccine among persons considered by the Advisory Committee on Immunization Practices to be at high risk for serious complications associated with influenza virus infection, health-care workers, and household contacts of children aged <6 months.
 

Report updates the 2004 recommendations by the Advisory Committee on Immunization Practices (ACIP) regarding use of influenza vaccine and antiviral agents. The 2005 recommendations include new or updated information regarding 1) vaccination of persons with conditions leading to compromise of the respiratory system; 2) vaccination of health-care workers; 3) clarification of the role of live, attenuated influenza vaccine in vaccine shortage situations; 4) the 2005–06 trivalent vaccine virus strains; and 5) the assessment of vaccine supply, timing of influenza vaccination, and prioritization of inactivated vaccine in shortage situations.
 

The Vaccine Safety Datalink and Kaiser Permanente Northern California established an automated system for rapid detection of potentially adverse events after vaccinations among its members. During the 2004–05 influenza season, in response to the influenza vaccine shortfall and resulting prioritization of vaccine distribution, this rapid analysis system also was used to assess influenza vaccination coverage weekly among KPNC members. The results indicated that KPNC followed Advisory Committee on Immunization Practices prioritization guidelines by targeting influenza vaccination to children aged 6–23 months and adults aged >65 years.
 

Describes U.S. and worldwide influenza activity during the 2004–2005 influenza season and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The weekly percentage of patient visits to U.S. influenza sentinel providers for ILI first exceeded the national baseline of 2.5% during the week ending January 1, 2005, and again for 13 consecutive weeks during the weeks ending January 15–March 26, 2005. ILI peaked at 5.4% during the week ending February 19, 2005. The percentage of deaths in the United States attributed to pneumonia and influenza exceeded the epidemic threshold during 8 consecutive weeks and peaked at 8.9% during the week ending March 5, 2005. During January 2004–June 28, 2005, a total of 108 human cases of avian influenza A (H5N1) infection resulting in 54 deaths were reported to WHO.
 

This report describes a surveillance system for laboratory-confirmed, influenza-associated hospitalizations in all age groups in Colorado that was implemented for the 2004–05 influenza season. The findings indicate that implementation of statewide, population-based surveillance for influenza-associated hospitalizations is feasible and useful for assessing the age-specific burden of serious influenza-associated morbidity and the relative severity of influenza seasons.

Describes U.S. influenza activity during the 2004–2005 influenza season. For the week ending March 26, 2005, a total of four states reported widespread influenza activity, and 15 states reported regional activity. The weekly percentage of patient visits to U.S. influenza sentinel providers for influenza-like illness first exceeded the national baseline of 2.5% during the week ending January 1, 2005, and exceeded the national baseline for 11 consecutive weeks from the week ending January 15, 2005, through the week ending March 26, 2005.
 

The Task Force on Community Preventive Services conducted systematic reviews to evaluate the effectiveness of interventions to improve targeted vaccination coverage among adults aged <65 years at high risk when implemented alone and in combination with other interventions. On the basis of strong evidence of effectiveness, the Task Force recommends the combination of one or more interventions to enhance access to vaccination services with at least one provider- or system-based intervention, and/or at least one intervention to increase client or community demand for vaccination.

Describes U.S. influenza activity during the 2004–2005 influenza season. For the week ending February 19, 2005, a total of 33 states reported widespread influenza activity, and 15 states reported regional activity. For the week ending February 19, the weekly percentage of patient visits to U.S. influenza sentinel providers for influenza-like illness was 5.7% and exceeded the national baseline of 2.5%.

Vaccination of health-care workers (HCWs) has been shown to reduce influenza infection and absenteeism, prevent mortality in their patients, and result in financial savings to sponsoring health institutions. However, influenza vaccination coverage among HCWs in the United States remains low; in 2003, coverage among HCWs was 40.1%. This report describes strategies implemented in three clinical settings that increased the proportion of HCWs who received influenza vaccination. The results demonstrate the value of making influenza vaccination convenient and available at no cost to HCWs.
 

In response to the influenza vaccine shortage during the 2004–05 season, the Connecticut Department of Public Health (DPH) operated a telephone hotline to 1) address questions from the public regarding the availability of influenza vaccine, 2) reduce the number of telephone inquiries to physicians and local health departments, and 3) advise callers regarding which groups were most at risk and in need of influenza vaccination. This report summarizes results of a retrospective survey of callers to the DPH influenza vaccine hotline during November 2004.

Describes U.S. influenza activity during the 2004–2005 influenza season. For the week ending January 1, 2005, two states reported widespread influenza activity, and 12 states reported regional activity. For the week ending January 1, the weekly percentage of patient visits to U.S. influenza sentinel providers for influenza-like illness was 3.0% and exceeded the national baseline of 2.5% for the first time this season. During the same week, 6.7% of recorded deaths were attributed to pneumonia and influenza, which was below the epidemic threshold of 7.9%.
 

Because of the unexpected shortage of inactivated influenza vaccine for the 2004–05 influenza season, the Advisory Committee on Immunization Practices recommended that the vaccine be reserved for persons in certain priority groups and asked others to defer or forego vaccination. This report summarizes data collected during December 1–11, 2004, to assess the use of influenza vaccine among adults and children and the primary reasons reported for not receiving vaccine.
 

During the shortage of inactivated influenza vaccine during the 2004–05 influenza season, the Advisory Committee on Immunization Practices recommended that the remaining vaccine supply should be reserved for 1) certain groups of persons at high risk for serious health problems from influenza, 2) health-care workers involved in direct patient care, and 3) close contacts of children aged <6 months (1). This report summarizes results of a survey conducted to determine 1) what proportion of persons at increased risk for influenza complications had been vaccinated as of the day of the survey, 2) what proportion sought vaccination but did not receive it because of the shortage, and 3) what factors might have dissuaded persons at high risk from seeking influenza vaccination.
 

Although vaccination has been a mainstay of influenza prevention, efforts to interrupt person-to-person transmission also are important. In October 2003, CDC recommended that health-care facilities implement a Universal Respiratory Hygiene Strategy, including providing masks or facial tissues in waiting rooms to persons with respiratory symptoms. This report summarizes the results of a February 2004 survey that assessed attitudes among U.S. adults regarding prevention of influenza-like illness, including use of vaccine and respiratory hygiene.
 

Vaccination of persons at risk for complications from influenza and pneumococcal disease is a key public health strategy for preventing associated morbidity and mortality in the United States. Risk factors include older age and medical conditions that increase the risk for complications from infections. To estimate influenza and pneumococcal vaccination coverage among populations at risk, CDC analyzed data from the 2003 Behavioral Risk Factor Surveillance System survey. This report summarizes the results of that analysis.
 

This report examines trends in influenza vaccination among Medicare beneficiaries during 1991--2002. Influenza vaccination increased steadily in this age group throughout the period, with a slight dip during the 2000--01 influenza season when production delays created a vaccine shortage. Overall, the most frequently cited reasons for not receiving influenza vaccine were 1) not knowing that influenza vaccination was needed and 2) concerns that vaccination might cause influenza or side effects. For the 2000--01 season, the vaccine shortage was cited as a leading reason for not receiving influenza vaccination. The report concludes that strategies are needed to educate older persons about the benefits of influenza vaccination and to address their concerns about vaccine safety.

Describes U.S. and worldwide influenza activity during May--October 2004 and reports the cumulative number of human illnesses and deaths attributed to avian influenza A (H5N1) reported to the World Health Organization (WHO) worldwide. The percentage of outpatient visits for influenza-like illness ranged from 0.4% to 0.8%. From December 2003 through October 25, 2004, a total of 44 laboratory-confirmed human cases of avian influenza A (H5N1) illness, including 32 deaths, were reported to WHO.
 

Influenza-associated pediatric mortality has been added to the list of conditions voluntarily reportable to the National Notifiable Diseases Surveillance System, beginning October 1, 2004.

The notice announces a potential delay in distribution of influenza vaccines from Chiron Corporation, one of the two major suppliers of inactivated influenza vaccine. Customers who ordered influenza vaccine from Chiron might need to reschedule planned clinics and other vaccination campaigns.

This report updates ACIP’s 2003 recommendations on the use of influenza vaccine and antiviral agents. Primary changes to previous recommendations are as follows: 1) healthy children aged 6--23 months and close contacts of children aged 0--23 months are added to the groups recommended for annual influenza vaccination; 2) inactivated vaccine is preferred over live, attenuated influenza vaccine (LAIV) for vaccination of household members, health-care workers, and others who have close contact with severely immunosuppressed persons; health-care workers who receive LAIV should refrain from contact with severely immunosuppressed patients for 7 days after vaccine receipt; and 3) severely immunosuppressed persons should not administer LAIV; however, other persons at high risk for influenza complications may administer LAIV.
 

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.
 

During December 2003---February 2004, outbreaks of highly pathogenic avian influenza A (H5N1) among poultry workers were reported in Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam. As of February 9, 2004, a total of 23 cases of laboratory-confirmed influenza A (H5N1) virus infections in humans, resulting in 18 deaths, had been reported in Thailand and Vietnam. In addition, 100 suspected cases in humans are under investigation by national health authorities in Thailand and Vietnam. CDC recommends that state and local health departments and health-care providers identify patients who could be infected by influenza A (H5N1) virus and take infection-control precautions when influenza A (H5N1) is suspected. CDC also ordered an immediate ban on import of all birds from affected countries and advised that travelers to countries in Asia with documented outbreaks should avoid poultry farms, contact with animals in live food markets, and surfaces that appear to be contaminated with feces from poultry or other animals.
 

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.
 

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.
 

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.
 

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%.
 

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.
 

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.