1. D.C. Department of Health
Evaluation of Influenza Vaccination Coverage in a High Risk Group, age ≥ 65 years, District of Columbia, 2001 – 2008
John O. Davies-Cole, PhD, MPH, George N.F. Siaway, PhD, Taralyn Lyon, MPH, Fern Johnson-Clarke, PhD, and Gerald Lucas, MS
D.C. Department of Health
November 2011

2. GET YOUR FLU SHOT

3. Background: Influenza – Important Public Health Problem
Healthy People Immunization Goal: 90% of individuals aged 65 years and older vaccinated against influenza.
Persons aged 65+ are concentrated in Wards 4 and 5 (Figure I).
Flu vaccination rates in the District of Columbia range from about 50% to about 75% from 2001 – 2008 (Behavioral Risk Factor Surveillance System).
Acute respiratory infections, including influenza, account for more than 56,000 deaths annually.
Highest rates of illness and death from influenza occur among those > 65 years and older and those with chronic illnesses. Vaccinations for influenza highly recommended for these groups.

4. Objectives and Methodology
Determine the coverage of influenza vaccines among individuals aged 65+ years
Evaluate the primary determinants of vaccination coverage among individuals aged 65+ years
Methodology
Data from the Behavioral Risk Factor Surveillance System Survey (BRFSS) were used to determine the association between pneumococcal and influenza immunization coverage in relation to socioeconomic conditions among individuals aged 65 years and older, living in the District of Columbia from 2001 through ArcGIS was used to show spatial coverage, and Univariate Chi-Square, t-test analyses and logistic regression were conducted using SAS version 9.1.

5. Results
Influenza vaccination rates of about 50% - 65% are generally found in parts of the northeast, southeast and southwest (Figure II).
The highest Influenza vaccination rates occurred in the northwest-southeast direction at about 75% percent for the 65+ age group (Figure III).
High /dissimilar clusters are seen in wards 6 and 7 (Figure IV).
Flu vaccination rates below 55% are generally dispersed throughout the rest of the Wards. Race was a consistent factor in vaccination receipt where blacks had significantly lower rates than whites (Table II).
Influenza vaccinations start high in the northwest and decrease towards the southeast. Influenza vaccinations also start low in the east and increase towards the west.
Vaccination rate for those who had some college education or were college graduates is 63%. Higher income shows more vaccination (68%) and those with access to insurance show 59% vaccination rate.
Individuals living in Ward 7 were more likely than those living in Ward 3 to report not receiving the influenza vaccination (OR: 1.47, 95% CI: 0.99 – 2.47).
Whites had the highest rate of influenza vaccination at 70% compared to blacks at 54%. The highest rates occurred among married individuals (63%), those who made $50,000 or more (68%), and those who were male (62%).

6. Figure I: Spatial Distribution of DC Residents, 65+ Years by Ward
The 65+ Age Group is concentrated in Wards 4 and 5 (Brown Polygons), and at a much lower level in Wards 3, 6 and 7 (Light Brown and Gold Polygons).

7. Figure II: Influenza Vaccination DC Residents, 65+ Years by Ward
High flu vaccinations are shown in Wards 3 at 75% (Brown Polygons) , and low vaccinations are shown in Ward 7 at 50% (Yellow Polygons). High age 65+ population lives in Wards 3, 4, 5 and 7. Only Ward 3 has the highest Influenza vaccinations for the Age 65+ group.

8. Figure III: Directional Distribution of Influenza Vaccination, 65+ Years by Ward
Figure 1: Influenza vaccinations start high in the northwest and decrease towards the southeast.
Influenza vaccinations start low in the east and increase towards the west.

9. Figure IV: Spatial Autocorrelation Analysis of Influenza Vaccination, 65+ Years by Ward
While the spatial distribution of Influenza vaccination is somewhat clustered, the pattern may be due to random chance (p < 0.1/90% Confidence level). Low Moran’s I (0.18) is due to the presence of similar Influenza vaccination rates. Z value of 1.36 falls within the critical value
(-1.65 and +1.65), meaning that at the 0.1 confidence level, we are 90% confident that the somewhat clustered pattern may be due to random chance.
Figure IV: While the spatial distribution of Influenza vaccination is somewhat clustered, the pattern may be due to random chance (p < 0.1/90% Confidence level).

10. Results Table I: Adjusted odds ratios for individuals aged 65 years and older not receiving vaccination by vaccination type
Ward (Reference = Ward 3)
Odds Ratio
Lower 95% CI
Upper 95% CI
Ward 1
1.00
0.63
1.59
Ward 2
1.18
0.81
1.72
Ward 3 -
Ward 4
1.05
0.73
1.52
Ward 5
1.42
0.96
2.11
Ward 6
1.45
Ward 7
1.47
0.98
2.20
Ward 8
1.56
0.99
2.47
Table I: The Odds Ratios are greater than one, meaning then the event (Influenza vaccinations) are more likely to happen than not, and there is a positive relationship between Influenza vaccinations and Wards.

11. Results Table II: Adjusted odds ratios for individuals aged 65 years and older not receiving vaccination by vaccination type
Sex (ref = Female)
Odds Ratio
Lower 95% (CI)
Upper 95% (CI)
Male
0.84
0.69
1.04
Female -
Marital Status (ref Married)
Married
Divorced or Separated
0.94
0.71
1.25
Widowed
0.95
0.73
1.23
Never Married or Member of an Unmarried Couple
1.17
0.85
1.6
Health Plan (ref = Insured)
Uninsured
1.16
0.63
2.12
Education (ref = Some College/College Graduate)
Some High School or Less
1.10
0.79
1.52
High School Graduate
0.99
0.77
1.28
Some College or College Graduate
The Odds Ratios show that the likelihood that male, divorced, widowed and high school graduate will get vaccinated is less likely to happen. Unmarried couple, uninsured and some high school or less are more likely to get vaccinated.
Race and Income interaction for Flu shot <0.000 (SS)
Flu shot Goodness of fit P= indicating model is good fit

12. Discussion
The study showed that only 59% of District residents had the flu vaccination. In order for the District to reach the 90% annual influenza and overall PPV, it will require strategies to promote vaccine-seeking behavior; increase the access to vaccination at nontraditional sites; increase community support; address safety concerns; and increase implementation of healthcare system changes and provider behaviors to promote and facilitate vaccination. An evaluation of behaviors and resistance toward vaccines should be conducted to develop Public Health interventions that improve community knowledge gaps in the District among this population.

13. REMEMBER TO GET YOUR FLU SHOT

14. Limitations
This study also only gathered self reported information. Therefore, there may be an underestimation of individuals who self reported not receiving PPV since the vaccination is received only once. In addition, a majority of interviews are conducted by landlines; therefore households that use cell phones only are less likely to participate in the study, which could result in an underestimate of the responses.

15. Conclusions
Interventions need to be developed that will aim at vaccination coverage among this vulnerable population in order to increase the rates of vaccination in the District of Columbia. Appropriate measures designed to target those who are already in contact with the healthcare system will be expedient in preventing possible missed opportunities for persons over 65 years old, especially in wards with the lowest vaccine coverage.

16. References
1 Healthy People Immunization and Infectious Diseases. Available at: Accessed January 20, Fry AM, Shay DK, Holmon RC, Curns AT, Anderson LJ. Trends in Hospitalizations for Pneumonia Among Persons 65 Years or Older in the United States, 1988 – JAMA, 2005;294(21): Accessed January 20, The National Network for Immunization Information. Vaccine information on Influenza. May Available at: Accessed January 20, National Center for Chronic Disease Prevention and Health Promotion. About the Behavioral Risk Factor Surveillance System. November Available at: Accessed January 20, 5 District of Columbia Department of Health, Center for Policy and Planning and Epidemiology. Behavioral Risk Factor Surveillance System 2007 Annual Report. May Available at: 1374,q, asp. Accessed January 20, National Center for Chronic Disease Prevention and Health Promotion. Behavioral Risk Factor Surveillance System Operational and User’s Guide Version 3.0. December 12, ftp://ftp.cdc.gov/pub/Data/Brfss/userguide.pdf. Accessed February 25, 2011.
High, similar and statistically significant clusters of Influenza-Pneumonia deaths are shown as red polygons (p = 0.01).

17. References
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9 Centers for Disease Control and Prevention. Prevention of pneumococcal disease: recommendations of the
Advisory Committee on Immunization Practices (ACIP). MMWR 1997;46:1-24.
10 Centers for Disease Control and Prevention. Prevention and control of influenza: recommendations of the
Advisory Committee on Immunization Practices (ACIP). MMWR 2004;53:1-40.
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