Early Predictors of Influenza Vaccination During the 2010-2011 Influenza Season Erin D. Kennedy, DVM, MPH1, Tammy Santibanez, PhD1, Gary Euler, DrPH, MPH1, Margrethe Montgomery2, Nicholas Davis2, Kennon Copeland2, James Singleton, MS1 and Cindy Weinbaum, MD, MPH1 1Immunization Services Division, NCIRD, Centers for Disease Control and Prevention, Atlanta, GA, 2NORC at the University of Chicago National Center for Immunization & Respiratory Diseases Immunization Services Division

Background National H1N1Flu Survey (NHFS) used in 2009-2010 influenza season NHFS provided weekly national estimates of H1N1 and seasonal influenza vaccination NHFS and BRFSS data combined to provide reliable estimates of coverage in priority populations* 2009-2010 first season in-season estimates were available Feedback about usefulness of both timely and area specific data National Flu Survey (NFS) planned for 2010-11 Good morning. The National H1N1 Flu Survey or NHFS was used during the 2009-2010 influenza season. The NHFS provided weekly national estimated of H1N1 and seasonal influenza vaccination coverage, intent of vaccination, opinions about the vaccines, and place of vaccination. NHFS and BRFSS data were combined to provide reliable national estimates of coverage in priority populations as well as state based estimates. The 2009-2010 season was the first season in-season influenza vaccination estimates were available. During this time, CDC received feedback about the usefulness of both timely and area specific data available during the 2009-2010 season. In response to this feedback, CDC planned to use similar coverage assessment methods during the 2010-2011 influenza season and the National Flu Survey or NFS was planned for the 2010-2011 influenza season. *MMWR 2010;59:44–8.

National Flu Survey (NFS): Objectives Provide national in-season estimates of current and projected vaccination coverage Provide national end-of-season coverage estimates Provide national in-season and end-of-season estimates of knowledge, attitudes, and practices regarding influenza vaccination Evaluate usefulness of in-season estimates for influencing national and local influenza campaigns Evaluate usefulness of local area data for local action Provide national in-season estimates of current and projected vaccination coverage Provide national end-of-season coverage estimates Provide national in-season and end-of-season estimates of knowledge, attitudes, and practices regarding influenza vaccination Evaluate usefulness of in-season estimates for influencing national and local influenza campaigns Evaluate usefulness of local area data for local action

methods

Methods: Overview Conducted November 1 -14, 2010 and March 3-31, 2011 Estimates reflect approximately the cumulative percent of persons vaccinated by the midpoint of the interview period (Nov 7) Random digit-dial telephone survey Landlines (80%) Cell phones (20%) 21 samples selected: 20 local areas and national Advance letter sent to landline households Conducted in both English and Spanish The sample was a list-assisted random digit-dial (RDD) sample of both landlines (80%) and cell telephones (20%). 21 samples were selected Sample telephone numbers for the survey were selected to be representative for 20 local areas in addition to a national sample. An advance letter was sent to landline households for which the telephone number could be matched to an address. The survey was conducted in both English and Spanish.

Methods: Household screening Based on the presence of a household member 18 years of age or older Cell telephone respondents were screened into the survey if they are a cell telephone only or cell telephone mostly household Landline sample: asked for the youngest male then for the youngest female Cell telephone sample, adult who answered the cell phone was asked about flu vaccinations Roster of all children in the household and one randomly selected Households were screened into the survey based on the presence of a household member 18 years of age or older. Cell telephone respondents were screened into the survey if they are a "cell telephone only" household (i.e., they reported that they do not maintain a landline telephone in their household) or a “cell telephone mostly” household (i.e., they maintain a landline but nonetheless make and receive most of their calls on a cell telephone). For the landline sample, the questionnaire asked for the youngest male 18 years and older currently at home. If there were no males at home, the questionnaire asked for the youngest female 18 years and older. For the cell telephone sample, the adult who answered the cell phone was asked about flu vaccinations. Additionally, the questionnaire rostered all children in the household younger than 18 years. One child was randomly selected and the adult respondent was asked about the flu vaccination status of that child.

Methods: Questionnaire Receipt of influenza vaccination since August 1, 2010 Intent to get vaccinated against influenza this season Place of influenza vaccination Doctor visits and recommendations for vaccination Respiratory illness since August 1, 2010 Opinions about influenza vaccination Vaccine efficacy Vaccine safety Perceived risk of getting sick with influenza if not vaccinated Acceptance of school-located vaccination The questionnaire asked about Receipt of influenza vaccination since August 1, 2010, Intent to get vaccinated against influenza this season, Place of influenza vaccination, recent Doctor visits and recommendations for vaccination, recent Respiratory illness, and Opinions about influenza vaccination inVaccine efficacy Vaccine safety Perceived risk of getting sick with influenza if not vaccinated Acceptance of school-located vaccination Opinion questions were asked on a four point likert scale.

Methods: Questionnaire Demographic characteristics Household Adult Child Medical conditions placing respondents at high risk for influenza related complications Contact with individuals at high risk for influenza related complications Work in a health care setting The questionnaire also asked demographic questions about the Household, the Adult respondent and the selected Child Other questions included Medical conditions placing respondents at high risk for influenza related complications, Contact with individuals at high risk for influenza related complications, and whether the respondents work in a health care setting.

Methods: Local Area Selection Existing CDC funded influenza programs Geographic diversity Adequate population size Existence of school-located influenza vaccination programs Ability to utilize data provided Agreement to make mid-season changes to their influenza vaccination campaign

NFS Local Areas This map shows the local areas selected in blue. Seattle-King County, WA; Fresno County, CA; Los Angeles County, CA; Maricopa County, AZ; Selected counties**, NM Selected counties¥, CO; Bexar County, TX; Houston, TX; Selected counties‡, AR; Selected counties€, MN; Davidson County, TN; Selected counties†, GA; Chicago, IL; Washtenaw County, MI

NFS Local Areas: Northeastern States This map shows the selected areas in the northeastern states: starting from the bottom of the map, they are: District of Columbia; Philadelphia, PA New York City, NY; Selected counties*, CT; Selected counties††, NH; Cumberland County, ME;

Methods: Local Area Collaboration Reviewed general questionnaire Could add two additional local area-specific questions Aided in design of data tables Data analyzed and delivered to local areas on Nov. 24 and to be delivered on April 11, 2011 Local areas reviewed the general questionnaire, could add 2 additional local area specific questions, and aided in design of data tables. Data was analyzed and delivered to local areas on Nov 24, 2010 and results from the March survey will be delivered on April 11, 2011

RESULTS

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 This table shows the influenza vaccination coverage and projected end of season coverage by age group from the November survey. The first column is the unweighted sample size, the next column the % of respondents already vaccinated and the last column the projected coverage. Projected coverage combines those already vaccinated and those answering that they definitely intend to get vaccinated during the 2010-2011 influenza season. *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 Overall, data was collected for almost 47,000 individuals. About 33% of individuals were already vaccinated against influenza and projected coverage was about 43%. *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 31% of children were already vaccinated with a projected coverage of 43%. *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 31% of children were already vaccinated with a projected coverage of 43%. The 6 month to 4 year old age group had the highest current coverage and projected coverage among children *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 About 34% of adults were already vaccinated with a projected coverage of 43%. *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Influenza vaccination coverage and projected end-of-season coverage* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Projected Coverage Overall 46908 32.8 ± 2.4 42.6 ± 2.6 By age group: 6m-4 years 2373 44.4 ± 11.2† 59.2 ± 11.9† 5-12 years 3789 28.2 ± 7.0 41.7 ± 7.4 13-17 years 2851 21.4 ± 9.3 30.0 ± 9.5 All children (6m-17years) 9013 30.6 ± 5.0 42.9 ± 5.3 18-49 years, HR†† 3170 32.8 ± 7.9 42.5 ± 8.3 18-49 years, non-HR†† 12731 19.9 ± 3.5 26.6 ± 3.8 50-64 years 11139 38.0± 4.7 50.6 ± 4.9 65+ years 9802 64.3± 4.8 74.0 ± 4.4 All adults 37895 33.5 ± 2.5 42.5 ± 2.7 18-49 year olds with no known medical conditions that place them at risk for influenza complications, the newly added group for influenza vaccination recommendation had the lowest current vaccination coverage (20%) and projected coverage (27%). Individuals 65 years of age and older, the age group with a long standing history of influenza vaccination recommendation, had the highest current coverage (64%) and projected coverage (74%). *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Monthly cumulative influenza vaccination coverage by selected age groups − Behavioral Risk Factor Surveillance System (BRFSS) and National Immunization Survey (NIS), August through November 2010 64.3 38.0 33.5 32.8 32.8 19.9 This slide shown by Dr Setse in her presentation, shows the monthly cumulative influenza vaccination coverage by selected age groups of children and adults from the BRFSS and the NIS from August through November 2010. The blue arrows indicate the NFS estimates. These estimates represent the coverage as of approximately Nov 7. All estimates obtained from the NFS fall within the estimates from these larger more established surveys. * High-risk conditions

Un–weighted sample size No. Adult influenza vaccination coverage and doctor visits and recommendation* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Visited doctor 22,268 41.4 ± 3.4 Recommendation 10,235 63.3 ± 5.4 No recommendation 11,992 23.2 ± 3.7 No doctor visit 14,832 23.2 ± 3.5 3,271 48.5 ± 9.0 11,516 17.1 ± 3.3 . *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Adult influenza vaccination coverage and doctor visits and recommendation* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Visited doctor 22,268 41.4 ± 3.4 Recommendation 10,235 63.3 ± 5.4 No recommendation 11,992 23.2 ± 3.7 No doctor visit 14,832 23.2 ± 3.5 3,271 48.5 ± 9.0 11,516 17.1 ± 3.3 . *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Adult influenza vaccination coverage and doctor visits and recommendation* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Visited doctor 22,268 41.4 ± 3.4 Recommendation 10,235 63.3 ± 5.4 No recommendation 11,992 23.2 ± 3.7 No doctor visit 14,832 23.2 ± 3.5 3,271 48.5 ± 9.0 11,516 17.1 ± 3.3 . *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Un–weighted sample size No. Adult influenza vaccination coverage and doctor visits and recommendation* as of Nov. 7, 2010 Un–weighted sample size No. Already Vaccinated % (95% CI) ** Visited doctor 22,268 41.4 ± 3.4 Recommendation 10,235 63.3 ± 5.4 No recommendation 11,992 23.2 ± 3.7 No doctor visit 14,832 23.2 ± 3.5 3,271 48.5 ± 9.0 11,516 17.1 ± 3.3 . *Projected coverage combines respondents already vaccinated and those answering they definitely intend to get vaccinated during the 2010-2011 season * * Percentages are weighted to the U.S. population; Confidence Interval half-width † Estimate may not be reliable, confidence interval half-width >10.0 †† HR=High risk: includes asthma, other lung problems, diabetes, heart disease, kidney problems, anemia, weakened immune system caused by a chronic illness or by medicines taken for a chronic illness.

Place of Influenza Vaccination This figure shows place of influenza vaccination for both children (shown in green) and adults (shown in blue). Percent of respondents is on the x axis and place of vaccination is on the y axis

Place of Influenza Vaccination Children were significantly more likely than adults to be vaccinated in a doctors office, while adults were significantly more likely than children to be vaccinated in a pharmacy, grocery store, and superstore.

Opinions about influenza vaccination How effective do you think the flu vaccination is in preventing the flu? Very Effective % (95% CI*) Somewhat effective Not too effective Not at all effective 37.6 ± 2.7 44.2 ± 2.8 6.2 ± 1.3 3.2 ± 0.8 How safe do you think the flu vaccine is? Very safe % (95% CI*) Somewhat safe Somewhat unsafe Very unsafe 46.1 ± 2.8 37.3 ± 2.8 9.4 ± 1.6 3.4 ± 1.1 If you do not get a flu vaccination this fall or winter, what are your chances of getting sick with the flu? Very high % (95% CI*) Somewhat high Somewhat low Very low 14.2 ± 2.0 27.7 ± 2.5 29.2 ± 2.5 25.7 ± 2.5

Positive opinions about influenza vaccination by vaccination status This figure shows the opinions about influenza vaccination by vaccination status. Vaccinated in blue and unvaccinated in grey. Each opinion question was asked on a four point likert scale. Responses 1 and 2 were combined and the % of respondents are shown on the on the y axis. Vaccinated respondents were significantly more likely than unvaccinated respondents to think influenza vaccination is very or somewhat effective. Vaccinated respondents were more likely than unvaccinated respondents to think influenza vaccination is very or somewhat safe. Vaccinated respondents were also significantly more likely than unvaccinated respondents to think they have a very or somewhat high chance of getting sick with the flu if unvaccinated. P<.01 for all three comparisons, based Wald Chi-square test comparing vaccinated versus unvaccinated.

Results Summary 18-49 year olds had the lowest current vaccination coverage (20%) and projected coverage (27%) Individuals 65 years of age and older had the highest current coverage (64%) and projected coverage (74%) NFS estimates were consistent with estimates obtained from BRFSS and NIS Children were significantly more likely to be vaccinated in a doctors office and adults were significantly more likely to be vaccinated in a retail location Doctor visits/recommendations associated with vaccination Vaccinated individuals were more likely to think vaccination is effective, safe, and that they have a high chance of getting sick with flu if unvaccinated

In-season Use of Results: National Level National Influenza Vaccination Week (NIVW) communication messages Help determine disparity areas for HHS/Walgreens vaccination voucher collaboration Brief ACIP and NVAC on coverage and projected coverage Communications with external partners (vaccine summit, etc) Validate BRFSS influenza like illness data Posted on CDC website http://www.cdc.gov/flu/professionals/vaccination/vaccinecoverage.htm

In-season Use of Results: Local Area NIVW communication messages Press releases Health Alert Network messages Outreach to providers Communications with external partners

Limitations Vaccination status is self-reported and are not validated with medical records Non-response bias may remain after weighting adjustments (CASRO response rate: 34.8% for landlines and 19.2% for cell phones)

Conclusions Barriers among certain age groups still remain after the universal influenza vaccination recommendation NFS was a useful tool to provide timely in-season data Assess projected influenza vaccination coverage Assess knowledge, attitudes, and practices Target education or outreach to certain populations Develop appropriate communication messages for NIVW Communicate with partners

Next Steps March survey concludes March 31, 2011 CDC and states will receive results mid-April CDC will use results to shape messaging for 2011-12 influenza season MMWR to be published early summer, 2011 Evaluation of use of results by local areas to be completed at end of May Further data analyses to determine predictors of influenza vaccination during the 2010-2011 season

Acknowledgements NCIRD, CDC NORC at the University of Chicago Cindy Weinbaum James Singleton Tammy Santibanez Gary Euler Pascale Wortley Bayo Arthur Kristine Sheedy Glen Nowak NORC at the University of Chicago Margrethe Montgomery Nicholas Davis Kennon Copeland

Acknowledgements Local Areas Public Health - Seattle & King County San Antonio Metropolitan Health District New Mexico State Department of Health Arkansas Department of Health Georgia Department of Community Health California Department of Public Health Chicago Department of Public Health Connecticut Department of Public Health District of Columbia Department of Health Colorado Department of Public Health & Environment Houston Department of Health & Human Services Maine Center for Disease Control and Prevention Maricopa County Department of Public Health Michigan Department of Community Health Minnesota Department of Health Metro Public Health Department (Nashville) New Hampshire Department of Health and Human Services New York City Department of Health and Mental Hygiene Philadelphia Department of Public Health

THANK YOU! Erin D. Kennedy: EDKennedy@cdc.gov The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention. National Center for Immunization & Respiratory Diseases Immunization Services Division