Place of Influenza Vaccination Among Adults—United States, 2010-11 Influenza Season FREE

MMWR. 2011;60:781-785

2 tables omitted

The 2010-11 influenza season was the first season after the 2009 influenza A (H1N1) pandemic and the first season that the Advisory Committee on Immunization Practices (ACIP) recommended influenza vaccination for all persons aged ≥6 months.¹ During the pandemic, many new partnerships between public health agencies and medical and nonmedical vaccination providers were formed, increasing the number of vaccination providers.² To provide a baseline for places where adults received influenza vaccination since the new ACIP recommendation and to help vaccination providers plan for the 2011-12 influenza season, CDC analyzed information from 46 states and the District of Columbia (DC) on influenza vaccination of adults aged ≥18 years for the 2010-11 season, collected during January—March 2011 by the Behavioral Risk Factor Surveillance System (BRFSS). This report summarizes the results of that analysis, which found that, for adults overall, a doctor's office was the most common place (39.8%) for receipt of the 2010-11 influenza vaccine, with stores (e.g., supermarkets or drug stores) (18.4%) and workplaces (17.4%) the next most common. For those aged 18-49 years and 50-64 years, a workplace was the second most common place of vaccination (25.7% and 21.1%, respectively). Persons aged ≥65 years who were not vaccinated at a doctor's office were most likely (24.3%) to have been vaccinated at a store. The results indicate that both medical and nonmedical settings are common places for adults to receive influenza vaccinations, that a doctor's office is the most important medical setting, and that workplaces and stores are important nonmedical settings.

BRFSS is a state-based, random-digit—dialed landline telephone survey collecting information from randomly selected persons aged ≥18 years among the noninstitutionalized, civilian population in 50 states and DC. BRFSS data are weighted for the probability of selection of a telephone number, the number of adults in a household, and the number of telephones in a household; a final poststratification adjustment is made for nonresponse and noncoverage of households without telephones.³ A total of 36,581 responses collected by BRFSS during January—March 2011 from adults in 46 states and DC who received an influenza vaccination during the 2010-11 influenza season were analyzed to estimate the percentage receiving the vaccine in various medical and nonmedical settings. The median state Council of American Survey and Research Organizations (CASRO) BRFSS response rate was 54.3%.

Respondents were asked whether they had received a flu vaccination during the past 12 months and if so, in which month and year and at what kind of place.* January interview data were available from 41 states; February interview data were available from 45 states and DC, and March interview data from 43 states and DC.† A total of 662 respondents who said they had received an influenza vaccination in the period before the 2010-11 influenza vaccine was available (i.e., during January—June 2010) were excluded from analysis. Also excluded were those for whom place of influenza vaccination data were missing (891 respondents), those who said they received their vaccinations in Canada or Mexico (21), those who said they did not know where they received their vaccination (61), and those who declined to answer the question (21).

Reported place of vaccination was analyzed by age group (18-49 years, 50-64 years, and ≥65 years) and divided into settings that were medical (doctor's office or health maintenance organization, health department, another type of clinic or health center, and hospital or emergency department) or nonmedical (senior, recreation, or community center; workplace; store; school; and some other kind of place). In addition to age group, medical or nonmedical setting was analyzed by sex, race/ethnicity, education, history of certain chronic conditions (i.e., asthma, diabetes, or cardiovascular disease) that increase the risk for influenza complications, health insurance status, time since last routine checkup, existence of a personal doctor, and cost as a barrier to seeing a doctor in the past 12 months. Tests of association between medical/nonmedical settings and other variables were conducted using chi-square tests with statistical significance at p<0.05.

Overall, a doctor's office was the most common place of vaccination (39.8%), followed by a store (18.4%), and workplace (17.4%) (Table 1). Among vaccinated adults aged 18-49 years, 32.2% were vaccinated at a doctor's office, 25.7% at a workplace, and 14.5% at a store. Similarly, adults aged 50-64 years most often reported vaccination at a doctor's office (38.8%), workplace (21.1%), or store (18.0%). Among adults aged ≥65 years, a greater percentage were vaccinated at a doctor's office (51.5%), and the second most common setting (24.3%) was a store. Overall, respondents with high-risk conditions were more likely to receive their vaccinations in a medical setting (69.4%) than those without these conditions (54.1%) (Table 2). Additionally, respondents with high-risk conditions were more likely to receive their vaccinations in a doctor's office than those without these conditions (49.1% versus 35.7%).

By type of setting, a greater percentage of respondents overall were vaccinated in medical settings (58.6%) than nonmedical settings (41.4%) (Table 2). The percentage of non-Hispanic whites receiving their influenza vaccination in a nonmedical setting (43.6%) was greater than the percentage of non-Hispanic blacks (28.7%) overall and in all age groups: 18-49 years (49.8% versus 31.9%), 50-64 years (45.9% versus 29.7%), and ≥65 years (34.1% versus 19.7%). The percentage of non-Hispanic whites (43.6%) receiving their influenza vaccination in a nonmedical setting also was greater than the percentage of Hispanics (34.3%) overall and among those aged 18-49 years (49.8% versus 35.1%), and 50-64 years (45.9 versus 32.0%). Among those aged ≥65 years, a greater percentage of Hispanics (33.9%) were vaccinated in nonmedical settings than non-Hispanic blacks (19.7%).

Overall, the percentage of persons vaccinated in nonmedical settings increased with education level: 27.5% for those with less than a high school education, 35.9% for high school graduates, and 46.7% for those who had attended college (Table 2). Overall, a greater proportion of persons whose last doctor visit for a routine checkup was ≥1 year ago (53.5%) received their vaccination in a nonmedical setting than those whose last doctor visit for a routine checkup was <1 year ago (38.8%); similar differences were observed across all age groups. Among adults overall and persons aged 50-64 years, vaccination in a nonmedical setting was significantly more common among those who reported not having a personal doctor than among those with a personal doctor: 48.5% versus 40.7% overall, and 53.4% versus 43.1% in the 50-64 age group (Table 2).

Reported by: Erin D. Kennedy, DVM, Tammy A. Santibanez, PhD, Leah N. Bryan, MPH, Pascale M. Wortley, MD, Gary L. Euler, DrPH, James A. Singleton, MS, Carolyn B. Bridges, MD, Cindy W. Weinbaum, MD, Immunization Svcs Div, National Center for Immunization and Respiratory Diseases; Lisa M. Koonin, MN, Influenza Coordination Unit, Office of Infectious Diseases, CDC. Corresponding contributor: Erin D. Kennedy, edkennedy@cdc.gov, 404-718-8733.

CDC Editorial Note: This study provides estimates of the proportion of U.S. adults in 46 states and DC receiving influenza vaccination in various medical and nonmedical settings during the 2010-11 influenza season and demonstrates the prominent role of physicians as vaccine providers and their potential influence on influenza vaccination. The most common place of vaccination for all age groups was a doctor's office. Previous studies have shown the importance of a recommendation by a health-care provider on influenza vaccination of adults.⁴ The findings that having had a doctor visit within the past year and having a personal doctor were associated with an increased likelihood of receiving influenza vaccination in a medical setting might be the result of health-care providers offering, recommending, or reminding patients about vaccination; these findings also likely reflect vaccination of adults with chronic conditions, who might have been more likely to have had a recent doctor visit or to have a personal doctor.

Although the majority of influenza vaccinations occurred in medical settings, an increasing proportion of influenza vaccinations took place in nonmedical settings. The proportion of adults vaccinated in stores (18.4%) during the 2010-11 season increased in each age group compared with the 1998-99 (5) and 2006-07 influenza seasons (National Immunization Survey [NIS]-Adult, unpublished data, 2011), when 5% and 7% of adults, respectively, were vaccinated in stores. This increase likely resulted partly from changes in state laws allowing pharmacists to administer influenza vaccinations to adults, and subsequently, more pharmacies offering influenza vaccinations. In 1999, only 22 states allowed pharmacists to administer influenza vaccinations to adults. In 2007, the number of states allowing this increased to 46, and in June 2009, all 50 states allowed pharmacists to administer influenza vaccinations (under prescribing protocols or prescription) to adults.⁶ The finding that adults whose last doctor visit for a routine checkup was ≥1 year ago were more likely to be vaccinated in a nonmedical setting suggests that the availability of influenza vaccination in nonmedical settings can complement health-care provider efforts by reaching populations less likely to be seen by providers.

Race/ethnicity was significantly associated with vaccination setting. Overall, non-Hispanic whites were more likely than non-Hispanic blacks and Hispanics to receive their vaccinations in nonmedical settings. Additionally, persons in all age groups who had attended college were more likely to receive their influenza vaccination in a nonmedical setting than those who had not attended college. Non-Hispanic white race/ethnicity and higher education have been associated previously with vaccination in nonmedical settings.^4,5 This association might result from place of vaccination preferences, differences in vaccine-seeking behavior, or differences in availability of nonmedical settings offering vaccinations; workplace vaccination might not be equally available to all socioeconomic groups, and supermarkets or drug stores in low-income neighborhoods might not offer vaccinations.

Overall, when comparing similar periods, influenza vaccination coverage has increased since the 2006-07 influenza season, with an estimated 38% of adults vaccinated in 2006-07 (BRFSS, unpublished data, 2011), compared with a preliminary estimate of 41% from 43 states in 2010-11.⁷ Using U.S. Census population estimates, this translates into approximately 84 million adults vaccinated in 2006-07, compared with approximately 94 million adults in 2010-11. During the 2006-07 influenza season, the most recent nonpandemic season for which data are available on place of vaccination, approximately 34% of vaccinees were vaccinated at a doctor's office, compared with 40% in 2010-11. This translates to approximately 28 million doses administered in a doctor's office in 2006-07, compared with approximately 37 million doses in 2010-11, an increase of approximately 33% (NIS-Adult, unpublished data, 2011). The estimated number of doses administered in stores increased from approximately 6 million in 2006-07 to approximately 17 million in 2010-11, an increase of approximately 180%. However, data for the 2006-07 season were obtained from NIS-Adult, and the survey methodology and coding of place differs from that of BRFSS.⁸ In addition, surveys might overestimate actual doses of vaccine administered.⁹ Therefore, estimates of total doses administered and comparisons of numbers vaccinated in different settings in 2006-07 and 2010-11 should be interpreted with caution.

The findings in this report are subject to at least four limitations. First, influenza vaccination status and place of vaccination were based on self-reported data and therefore might be subject to recall bias or social desirability bias.⁹ Second, BRFSS data were obtained from landline telephone surveys and did not include households with no telephone service or households with cellular telephone service only; in addition, the BRFSS survey had a low median state CASRO response rate of 54.3%. Third, health-care workers vaccinated in medical settings might have reported that they were vaccinated at the workplace; therefore, the percentage of vaccinations in nonmedical settings might be overestimated. Finally, four states were not represented in this analysis, and estimates might differ once data from all states are available.

This report highlights the roles of both medical and nonmedical settings in influenza vaccination of adults. Limited data are available on trends in place of vaccination using similar methodologies; the last available BRFSS data for all states are from the 2001-02 influenza season, and data from 14 states were collected in 2004. Monitoring place of vaccination annually with consistent methodology can help identify new trends in place of vaccination among adults, can help shape future influenza immunization programs targeted at specific groups, and can identify potential new partnerships. These results also can help guide development of strategies for achieving Healthy People 2020 targets for influenza vaccination of adults (e.g., 80% of noninstitutionalized adults aged 18-64 years and 90% of those aged ≥65 years).¹⁰

During the 2009 H1N1 pandemic, many new partnerships between public health agencies and medical and nonmedical organizations were formed, increasing the number of influenza vaccination providers.

What is added by this report?

During the 2010-11 influenza season, the most common place of vaccination for all age groups was a doctor's office (39.8%). The proportion of adults vaccinated in stores (18.4%) increased, compared with data from the 1998-99 and 2006-07 influenza seasons.

What are the implications for public health practice?

Understanding where adults receive influenza vaccinations can help shape future influenza immunization programs, identify new potential partners for vaccination programs, and help guide development of strategies for reaching Healthy People 2020 targets for influenza vaccination of adults.

*The question asking what kind of place was open-ended and coded by BRFSS interviewers, using one of the following options: a doctor's office or health maintenance organization; a health department; another type of clinic or health center (e.g., a community health center); a senior, recreation, or community center; a store (e.g., supermarket or drug store); a hospital (e.g., inpatient); an emergency department; workplace; some other kind of place; a school; don't know/not sure.

† January interview data were missing from DC, Illinois, Michigan, New Hampshire, North Carolina, and Utah. February interview data were missing from South Dakota. March interview data were missing from Louisiana, Michigan, and South Dakota. Interview data for all 3 months were missing from California, Nevada, Oklahoma, and Oregon.

REFERENCES

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