Influenza Vaccination Coverage among Children and Adults — United States, 2008–09 Influenza Season

GL Euler, DrPH; PJ Lu, PhD, MD; A Shefer, MD; JA Singleton, MS; A Fiore, MD; M Town, MS; L Balluz, ScD


Morbidity and Mortality Weekly Report. 2009;58(39):1091-1095. 

In This Article

Abstract and Introduction


Before 2008, the Advisory Committee on Immunization Practices (ACIP) had recommended annual vaccination for influenza for persons aged ≥50 years, 18–49 years at higher risk for influenza complications, and 6 months–4 years.[1] In 2008, ACIP expanded the recommendations to include all children aged 5–18 years, beginning with the 2008–09 season, if feasible, but no later than the 2009–10 season.[2] This expansion added 26 million children and adolescents to groups recommended for routine influenza vaccination. To assess vaccination uptake among children and adults during the 2008–09 influenza season, CDC analyzed data from the Behavioral Risk Factor Surveillance System (BRFSS) in 19 states, which represent 43% of the U.S. population. This report summarizes the results of the analysis, which indicated that reported influenza vaccination coverage of ≥1 doses was 40.9% for ages 6–23 months, 32.0% for 2–4 years, and 20.8% for 5–17 years. Among adults, reported coverage was 32.1% for persons aged 18–49 years with high-risk conditions, 42.3% for persons 50–64 years, and 67.2% for persons ≥65 years. These results are consistent with previous studies that have found no significant increases in vaccination coverage for any of these age groups over previous seasons.[1–5] * These 2008–09 season estimates provide a baseline for assessing implementation of the 2008 recommendation for school-aged children. Attaining higher coverage rates likely will require additional vaccination programs in schools and expanded vaccination services in provider offices.[6,7]

BRFSS is a state-based, random-digit-dialed telephone survey that collects information from approximately 414,000 randomly selected, noninstitutionalized adults aged ≥18 years. Data are collected monthly in all 50 states, the District of Columbia (DC), Puerto Rico, the U.S. Virgin Islands, and Guam. Collected data are weighted by age, sex, and race/ethnicity to reflect each state's adult population. To determine influenza vaccination status, respondents were asked, "During the past 12 months, have you had a flu shot?" and "During the past 12 months, have you had a flu vaccine that was sprayed in your nose?" Persons who answered "yes" to either question were asked what month and year their most recent influenza vaccination was received. For the January and February 2009 BRFSS survey conducted just before the beginning of the 2009 H1N1 influenza outbreak, 19§ of the 46 states and DC that were participating volunteered to add two questions to assess seasonal influenza vaccination in children. The questions asked respondents to indicate whether a randomly selected child in each eligible household had received an influenza vaccination within the past 12 months and in what month (for those who had received a vaccination). Weighted data from these 19 states were combined to estimate coverage levels for adults and children for the 2008–09 season. Vaccination coverage estimates are based on vaccinations during August–December.

During the 2008–09 influenza season, the Council of American Survey and Research Organizations (CASRO) state response and cooperation rates (including median and range for each) for these 19 states were 53.7% (37.9–66.1) and 76.7% (57.8–86.4), respectively. Respondents who reported unknown influenza vaccination status (don't know, refused, missing, or blank or incomplete date of vaccination) (4.8%) were excluded from the analysis. Software for statistical analysis of complex survey data was used to calculate point estimates and 95% confidence intervals. Statistical differences between groups were determined using the t-test (p≤0.05).

Seasonal influenza vaccination coverage estimates for adults in the 19 states were 67.2% (ages ≥65 years), 42.3% (50–64 years), 22.2% (18–49 years), and 32.1% (18–49 years, with diabetes, asthma, or heart disease) (Table). Among children, coverage estimates were 40.9% (ages 6–23 months), 32.0% (2–4 years), 20.8% (5–17 years), and 24.0% (6 months–17 years). Among all persons aged ≥6 months, coverage was higher among non-Hispanic whites (36.7%) compared with non-Hispanic blacks (24.9%) (p<0.001) and Hispanics (22.0%) (p<0.001). Age-specific coverage levels were higher among non-Hispanic whites compared with non-Hispanic blacks for the two oldest age groups (50–64 years and ≥65 years) (p=0.002 and p=0.03), and compared with Hispanics for children aged 2–4 years (p<0.001).

During the 2004–05 season, because of a vaccine shortage, BRFSS-estimated coverage levels dropped by 9 percentage points among persons aged ≥65 years, 20 points among persons aged 50–64 years, and 12 points among persons aged 18–49 years with high-risk conditions. Coverage levels among adults for the past four seasons (Figure) have increased to nearly the same levels of those preceding 2005–04 season. The 2008–09 coverage estimates were still lower than those during 2003–04, the season before the vaccine shortage, by 5.3, 3.2, and 4.7 percentage points, respectively, for the ≥65, 50–64, and 18–49 years age groups.


Estimated influenza vaccination coverage among persons aged ≥18 years — United States, Behavioral Risk Factor Surveillance System (BRFSS), 1992–93 through 2008–09 influenza seasons*
* Data for the 2008–09 season were obtained from a survey conducted in 46 states and the District of Columbia, primarily during January and February 2009, and include vaccinations given during August–December 2008. Data for the 2007–08 season are based on February–August interviews only and vaccinations given during September 2007–January 2008. All other data points are based on February–August interviews only and vaccinations given in the preceding 12 months of interview.
Persons who had asthma or diabetes were identified as having high-risk conditions for the 2000–01 through 2004–05 seasons, and persons with asthma, diabetes, or heart diseases were identified as having high-risk conditions for the 2005–06 through 2008–09 seasons.
§ The Advisory Committee on Immunization Practices added a recommendation to vaccinate all persons aged 50–64 years, beginning with the 2000–01 influenza season. BRFSS also began collecting influenza vaccination data in the 2000–01 influenza season for persons aged 50–64 years and for persons aged 18–49 years with selected high-risk conditions.

* CDC. Early release of selected estimates based on data from the January–March 2009 and the January–March 2008 National Health Interview Survey receipt of influenza vaccination. Available, respectively, at and at
Additional information and survey questions available at
§ Alaska, California, Connecticut, Delaware, Hawaii, Illinois, Iowa, Kansas, Maine, Michigan, Nevada, New Mexico, Ohio, Texas, Utah, Washington, West Virginia, Wisconsin, and Wyoming.
The CASRO response rate is the product of three other rates: the resolution rate, which is the proportion of telephone numbers that can be identified as either for a business or a residence; the screening rate, which is the proportion of qualified households that complete the screening process; and the cooperation rate, which is the proportion of contacted eligible households for which a completed interview is obtained.
** CDC data for the 2007–08 season were in preparation for publication at the time of this report.


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