Influenza and Pneumococcal Vaccination Coverage Among Persons Aged >65 Years --- United States, 2004--2005

Vaccination of persons at increased risk for complications from influenza and pneumococcal disease is a key public health strategy in the United States. During the 1990--1999 influenza seasons, approximately 36,000 deaths were attributed annually to influenza infection, with approximately 90% of deaths occurring among adults aged >65 years (1). In 1998, an estimated 3,400 adults aged >65 years died as a result of invasive pneumococcal disease (2). One of the Healthy People 2010 objectives is to achieve 90% coverage of noninstitutionalized adults aged >65 years for both influenza and pneumococcal vaccinations (objective 14-29) (3). To assess progress toward this goal, this report examines vaccination coverage for persons interviewed in the 2004 and 2005 Behavioral Risk Factor Surveillance System (BRFSS) surveys. The 2004--05 influenza season was characterized by an influenza vaccine shortage. As a result, the Advisory Committee on Immunization Practices (ACIP) issued recommendations that influenza vaccine be reserved for persons in priority groups, including persons aged >65 years, and that others should defer vaccination until supply was sufficient (4). The results of this assessment indicated that, overall, influenza vaccination coverage was lower in the 2005 survey year than in 2004, whereas pneumococcal vaccination coverage was nearly unchanged from 2004 to 2005. In both years, influenza and pneumococcal vaccination coverage varied from state to state. Continued measures are needed to increase the proportion of older adults who receive influenza and pneumococcal vaccines; health-care providers should offer pneumococcal vaccine all year and should continue to offer influenza vaccine during December and throughout the influenza season, even after influenza activity has been documented in the community.

BRFSS is an ongoing, state-based, random-digit--dialed telephone survey of the U.S. civilian, noninstitutionalized population aged >18 years. All 50 states, the District of Columbia (DC), and three U.S. territories participate in the survey. In 2004 and 2005, respondents were asked, "During the past 12 months, have you had a flu shot?" and "Have you ever had a pneumonia shot?" The median state/area CASRO response rates were 52.7% (range: 32.2%--66.6%) in 2004 and 51.1% (range: 34.6%--67.4%) in 2005 (5,6). In 2004, a total of 303,822 persons responded, of whom 68,514 (22.6%) were aged >65 years; in 2005, a total of 356,112 persons responded, of whom 87,351 (24.5%) were aged >65 years. Respondents who reported unknown influenza (0.3% in 2004 and 2005) or pneumococcal (3.1% in 2004 and 3.5% in 2005) vaccination status were excluded from the analysis. In addition to vaccination coverage for 2004 and 2005, a secondary analysis of influenza vaccination restricted to persons interviewed during January--June of each survey year was conducted because the majority of these persons were reporting specifically on vaccination received during the preceding September through December; thus, they would have received vaccine for a single influenza season. Vaccination levels were estimated for the 50 states, DC, Puerto Rico, and the U.S. Virgin Islands. Hawaii did not report data to BRFSS in 2004. Data were weighted by age, sex, and race, adjusting for probabilities of selection, not having a landline telephone, and nonresponse, to reflect the estimated adult population. Overall vaccination coverage was calculated as the weighted mean of state percentages. Statistical software was used to calculate percentage estimates and 95% confidence intervals (CIs).

Overall, in 2004, 67.6% (CI = 66.9%--68.3%) of respondents aged >65 years reported having received influenza vaccine during the preceding 12 months. Vaccination coverage levels ranged from 35.3% (Puerto Rico) to 78.8% (Colorado), with a median of 67.9% (Table). In 2005, 63.3% (CI = 62.7%--64.0%) of respondents aged >65 years reported having received influenza vaccine during the preceding 12 months. Vaccination coverage levels ranged from 32.0% (Puerto Rico) to 78.2% (Minnesota), with a median of 65.5%. The median change in influenza vaccination coverage from the 2004 to the 2005 survey was -5.1%. In 16 states, the decline in influenza vaccination coverage was statistically significant (p<0.05). In 13 of the 16 states, the coverage decline was <10%.

Overall, during the first 6 months of 2004, 73.8% (CI = 72.8%--74.7%) of respondents aged >65 years reported having received influenza vaccine, compared with 64.0% (CI = 63.1%--64.9%) of respondents aged >65 years in the first 6 months of 2005. Vaccination coverage in the first half of 2004 ranged from 38.2% (Puerto Rico) to 82.5% (Colorado), with a median of 75.2%, and in the first half of 2005 from 36.9% (Puerto Rico) to 80.2% (Minnesota), with a median of 65.5%. Influenza vaccination coverage decreased in all but two states/areas; the declines ranged from 23.7% to 3.2%, with a median of 12.0%. The decline in coverage was statistically significant in 44 states, and was <10% in nine of the 44 states.

In 2004, the overall proportion of respondents aged >65 years reporting ever having received pneumococcal vaccine was 63.4% (CI = 62.7%--64.1%). Vaccination coverage ranged from 32.7% (Puerto Rico) to 71.6% (Montana), with a median of 64.6%. In 2005, the overall proportion of respondents aged >65 years reporting ever having received pneumococcal vaccine was 63.7% (CI = 63.1%--64.4%). Vaccination coverage ranged from 28.3% (Puerto Rico) to 71.7% (North Dakota), with a median of 65.7%. In three states, the increase in pneumococcal vaccination coverage from 2004 to 2005 was statistically significant, whereas one state had a statistically significant decline in pneumococcal vaccination coverage during this period. In the three states with a significant increase in coverage, the increase ranged from 6.8% to 10.5%. Among persons aged >65 years vaccinated against influenza, 22.8% in 2004 and 20.6% in 2005 reported never having received pneumococcal vaccine.

Reported by: MC Lindley, MPH, GL Euler, DrPH, Immunization Svcs Div, National Center for Immunization and Respiratory Diseases (proposed); T Shimabukuro, MD, EIS Officer, CDC.

Editorial Note:

These BRFSS data indicate that among persons aged >65 years, overall influenza vaccination coverage declined from 67.6% to 63.3% from 2004 to 2005, whereas pneumococcal vaccination coverage was nearly unchanged (63.4% and 63.7%, respectively). Both influenza and pneumococcal vaccination levels among adults aged >65 years remain below the Healthy People 2010 objective of 90% coverage nationwide.

Estimated influenza vaccination coverage for the first 6 months of each year suggests that adults aged >65 years were affected by the 2004--05 vaccine shortage, with a median coverage decline of 12.0% from 2004 to 2005. Approximately 61 million doses of influenza vaccine were produced during the 2004--05 influenza season, compared with 95 million and 87 million doses during the 2002--03 and 2003--04 seasons, respectively. Although the supply interruption reduced influenza vaccination coverage in priority groups compared with the previous year, high levels of coverage nonetheless were achieved by diverting available vaccine to priority groups. This measure was supported by a special nationwide BRFSS survey administered and analyzed monthly to monitor vaccine uptake by priority groups.

Management of the 2004--05 influenza season vaccine shortage was complicated by the lack of a centralized system to manage information on vaccine ordering and receipt from all manufacturers and distributors. Recurring vaccine supply concerns during the 2005--06 influenza season, resulting from one vaccine manufacturer's inability to produce as much vaccine as originally planned, again highlighted the challenges posed to influenza vaccination with few manufacturers producing the vaccine. During the 2006--07 influenza season, three manufacturers will be providing trivalent inactivated influenza vaccine, and a fourth will continue to supply live attenuated influenza vaccine (licensed for use in persons aged 5--49 years with no underlying medical conditions), thereby reducing vulnerability to supply or distribution challenges. CDC is working with manufacturers and distributors to improve the availability, timeliness, and completeness of a vaccine-supply tracking system first initiated during the 2004--05 influenza season.

Even during years with limited influenza vaccine availability, millions of doses remain unused at the end of the influenza season: in each season since 2000--01, 4%--13% of influenza vaccine doses produced were not distributed (CDC, unpublished data, 2006). Because influenza activity often does not peak until January or later, ACIP and CDC recommend that health-care providers continue to offer influenza vaccine to patients during December and later months. The National Influenza Vaccine Summit will promote the importance of continuing to offer influenza vaccine after the optimal period of October--November. In addition, expanding the production capacity of influenza vaccine manufacturers is needed to ensure availability of influenza vaccine and vaccination before the start of influenza virus circulation.

On the basis of data from the National Health Interview Survey (NHIS), pneumococcal vaccination coverage increased by 32% (from 42.6% to 56.3%) among persons aged >65 years from 1997 to 2005, but coverage has remained nearly unchanged since 2002 (56.2%).* In the 2004 and 2005 BRFSS surveys, approximately 20% of persons aged >65 years who said they received influenza vaccine reported never having received a pneumococcal vaccination, indicating missed opportunities for pneumococcal vaccine administration at the time of influenza vaccination. Offering pneumococcal vaccine with influenza vaccination should facilitate improvement in pneumococcal vaccination coverage.

The findings in this report are subject to at least three limitations. First, influenza and pneumococcal vaccination status were based on self-report and were not validated. The validity of self-reported pneumococcal vaccination is lower than that of influenza vaccination (7). Second, median BRFSS response rates were low in both years (<60%), and BRFSS does not reach persons without landline telephones. Finally, because BRFSS surveillance is conducted during a 12-month period, questions regarding receipt of influenza vaccination do not reflect a single influenza season. The influenza vaccination estimates restricted to the first 6 months of each survey year mitigate the effects of this limitation.

BRFSS results have been compared with results from NHIS, a household-based, face-to-face interview survey with higher response rates. Although NHIS uses a national sampling scheme and BRFSS uses a state-based scheme, comparisons indicate similar trends; however, some subgroup differences are more pronounced in BRFSS. Vaccination coverage estimates in BRFSS surveys are consistently higher than NHIS estimates (8), although receipt of influenza and pneumococcal vaccination is self-reported in both surveys. NHIS estimates for 2005 indicate 59.5% influenza and 56.3% pneumococcal vaccination coverage in persons aged >65 years, compared with 63.3% and 63.7%, respectively, in the 2005 BRFSS.

Variation in influenza and pneumococcal vaccination coverage observed among states/areas suggests that coverage for both vaccines can be improved. Current projections indicate that the supply of influenza vaccine for the 2006--07 season will be 100--115 million doses, sufficient to meet the estimated demand among groups recommended for influenza vaccination.^† This estimate might be affected by changes in anticipated yield and by the potential licensing of an additional vaccine. Strategies such as standing orders, reminder/recall systems, and offering vaccinations to hospitalized patients before discharge have been shown to improve vaccination coverage in adults (9) and should be used to facilitate progress toward the Healthy People 2010 objective of 90% coverage with both influenza and pneumococcal vaccines among persons aged >65 years.

Acknowledgment

This report is based on data contributed by state BRFSS coordinators.

References

1. Thompson WW, Shay DK, Weintraub E, et al. Mortality associated with influenza and respiratory syncytial virus in the United States. JAMA 2003;289:179--86.
2. Robinson K, Baughman W, Rothrock G, et al. Epidemiology of invasive Streptococcus pneumoniae infection in the United States, 1995--1998. JAMA 2001;285:1729--35.
3. US Department of Health and Human Services. Healthy people 2010 (conference ed, in 2 vols). Washington, DC: US Department of Health and Human Services; 2000. Available at http://www.health.gov/healthypeople.
4. CDC. Interim influenza vaccination recommendations, 2004--05 influenza season. MMWR 2005;53:923--24.
5. CDC. 2004 BRFSS summary data quality report. Atlanta, GA: US Department of Health and Human Services, CDC; 2005.
6. CDC. 2005 BRFSS summary data quality report. Atlanta, GA: US Department of Health and Human Services, CDC; 2006.
7. MacDonald R, Baken L, Nelson A, Nichol KL. Validation of self-report of influenza and pneumococcal vaccination status in elderly outpatients. Am J Prev Med 1999;16:173--7.
8. CDC. Influenza and pneumococcal vaccination levels among persons aged >65 years---United States, 2001. MMWR 2002;51:1019--24.
9. Task Force on Community Preventive Services. Recommendations regarding interventions to improve vaccination coverage in children, adolescents, and adults. Am J Prev Med 2000;18(Suppl 1):S92--S96.

^† Additional information is available at http://www.cdc.gov/flu/professionals/vaccination/pdf/targetpopchart.pdf.

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Date last reviewed: 10/4/2006