Factors Affecting Tetanus-containing Vaccine Coverage among Teens — United States, 2007 National Immunization Conference April 22, 2010 - Atlanta, GA Colleen Wichser, MPH Health Services Research and Evaluation Branch Immunization Services Division National Center for Immunization and Respiratory Diseases

Outline Background Objectives Methods Results Discussion Conclusions

Vaccine-Preventable Disease Background Prevaccine Era1 Postvaccine Era1,2 Vaccine-Preventable Disease Reported cases (at peak) Reported deaths Reported cases, 2007 2 Reported deaths, 2004 Diphtheria 30,508 (1938) 3,065 (1936) Tetanus 601 (1948) 511 (1947) 28 4 Pertussis 265,269 (1934) 7,518 (1934) 10,454 27 Persons aged ≥10 years accounted for ~ 60% of the reported pertussis cases in 2007 For the pre- and post- vaccine eras, this slide allows comparison of epidemiologic trends in diseases currently preventable with tetanus-containing vaccines. As shown in the 4th column, since the prevaccine era, the annual number of reported tetanus and diphtheria cases has dramatically decreased, to near or at zero. In contrast, in 2007, 10,454 cases of pertussis were reported. Importantly, adolescents and adults have recently accounted for an increasing proportion of reported pertussis cases. Persons aged 10 years and older accounted for approximately 60% of reported pertussis cases in 2007. Waning immunity in adolescents and adults and other factors might be contributing to the increasing proportion of reported pertussis cases among adolescents and adults. Roush SW, Murphy TV, Vaccine-Preventable Disease Table Working Group. Historical comparisons of morbidity and mortality for vaccine-preventable diseases in the United States. JAMA 2007;298(18):2155-63. CDC. Summary of notifiable diseases — United States, 2007. MMWR. 2009;56(No. 53):1-94

2 Tdap vaccines licensed by U.S. FDA Spring 2005 2 Tdap vaccines licensed by U.S. FDA June 2005 ACIP recommends routine Tdap vaccination for adolescents aged 11–18 years. Preferred age for Tdap vaccination is 11–12 years. Boosting against pertussis for adolescents and adults became possible in 2005. That spring, two tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine products were licensed by the U.S. Food and Drug Administration for use in the United States. In June 2005, the Advisory Committee on Immunization Practices (ACIP) recommended that adolescents aged 11–18 years receive a single dose of Tdap, instead of Td, for booster immunization against tetanus, diphtheria, and pertussis. The preferred age for Tdap vaccination is 11 – 12 years. Tdap = Tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine FDA = Food and Drug Administration ACIP = Advisory Committee on Immunization Practices 4

Background According to 2007 NIS–Teen data1, Td/Tdap vaccination coverage among adolescents: 13–17 years: 72.3% 13–15 years: 69.3% Above estimates indicate coverage falls short of Healthy People 2010 target According to the 2007 NIS–Teen results, vaccination coverage among adolescents aged 13–17 years with ≥ 1 doses of Td/Tdap after age 10 years was 72.3%. Likewise, coverage for teens aged 13–15 years was 69.3%. This latter estimate falls short of the Healthy People 2010 target of 90% vaccination coverage with one or more doses of tetanus-diphtheria booster among adolescents aged 13 to 15 years. Identifying factors associated with Td/Tdap vaccination could facilitate the development of strategies to increase coverage among adolescents. This leads me to the objectives of the study… 1. CDC. Vaccination coverage among adolescents aged 13–17 years — United States, 2007. MMWR 2008;57(40):1100-3.

Objectives To obtain an additional Td/Tdap national vaccination coverage estimate among adolescents in the United States To identify factors associated with receipt of Td/Tdap among adolescents aged 13–17 years This study had two main objectives. First, we wanted to obtain an additional national estimate of Td/Tdap vaccination among adolescents in the United States. We also wanted to identify factors associated with Td/Tdap vaccination among adolescents aged 13–17 years.

Methods: Survey 2007 National Survey of Children’s Health Random-digit-dialed telephone survey administered between April 2007 and July 2008 1 sample child (<18yrs) selected from each household; parent or guardian served as respondent Interview completion rate: 66% To accomplish our objectives, we used cross-sectional data from the 2007 National Survey of Children’s Health. The 2007 NSCH was a random-digit-dialed telephone survey administered between April 2007 and July 2008, with nearly 80% of the interviews completed in 2007. One child, aged less than 18 years, was randomly selected from all the children in each identified household. The respondent was a parent or guardian who knew about the child’s health and health care. Interviews were completed in 66% of identified households.

Methods: Outcome Measure Question: Has [S.C.] received a tetanus booster shot or Td or Tdap shot since (he/she) turned 11 years of age? Vaccination and health care visit history based on parental report only Written shot cards were not referenced Responses of “don’t know” or “refused to answer” (5.9%) were excluded from the analysis Receipt of ≥1 doses of Td/Tdap since turning 11 years of age was the outcome variable of interest. Respondents were asked: Has the sample child received a tetanus booster shot or Td or Tdap shot since he or she turned 11 years of age? Vaccination and health care visit history were based on parental report only; provider validation was not conducted and written shot cards were not referenced. Responses of “don’t know” or refused to answer were excluded from the analysis. These responses only accounted for 5.9% of all responses given.

Methods: Analysis Bivariate and Multivariate Analyses Factors associated with vaccination Demographic, maternal, and household characteristics Insurance status and health care utilization variables Backward selection procedure Full model included two interaction terms Adjusted odds ratios and 95% confidence intervals are reported We used bivariate and multivariate logistic regression analyses to evaluate and model factors associated with Td/Tdap vaccination. Demographic, maternal, and household characteristics as well as insurance status and health care utilization variables were examined. To identify independent predictors of vaccination, a backward selection procedure was used in which predictors with the largest P values were dropped until all remaining predictors were significant at alpha = 0.05. Two interaction terms, age*preventive health care visit and census region*MSA were included in the full multivariate model. Adjusted odds ratios and 95% confidence intervals are reported. All data were analyzed using SAS version 9.2 and SUDAAN version 10. *** Also looked at MSA*preventive health care visit. Not significant at alpha = 0.05.

Characteristics of Study Participants (N=31,001) Wtd % Age 13 y 18.9 14 y 22.0 15 y 19.0 16 y 20.8 17 y 19.3 Sex Female 48.7 Race/ethnicity White NH 59.0 Black NH 15.8 Hispanic 18.1 Other NH 7.1 Census Region Northeast 17.5 Midwest 22.4 South 35.9 West 21.2 Preventive Health care visit in past 12mo? Yes 84.0 Insurance status Private 66.0 Public 23.9 Uninsured 10.1 Analyses included data pertaining to 31,001 adolescents aged 13 – 17 years. The sample was roughly evenly distributed across age groups and was evenly divided between males and females. The majority of the study participants were white, non-Hispanic. Thirty-sex percent of participants were from the South, 22% from the Midwest, 21% from the West, and 18% from the Northeast. Approximately 84% of households reported that the adolescent had attended a preventive health care visit in the 12 months prior to the interview. About two-thirds of adolescents had private health insurance at the time of the interview and about 10% were uninsured.

Estimated vaccination coverage levels of Td/Tdap by age, 2007 NSCH This slide shows estimated vaccination coverage levels of Td/Tdap by age. The x-axis indicates age in years while the y-axis represents the percentage of teens vaccinated. Confidence intervals are shown in red. Overall, as shown in the far right column, vaccination coverage with ≥ 1 doses of Td/Tdap was 88.2% (95% CI: 87.2–89.1). As you can see, vaccination coverage with ≥ 1 doses of Td/Tdap increased linearly with age, with the exception of adolescents aged 17 years. Vaccination coverage for teens aged 17 years was lower than coverage for teens aged 16 years. However, this difference is not likely statistically significant.

Estimated Td/Tdap vaccination coverage by sociodemographic characteristics % UTD Unadjusted OR (95% CI) Sex Female 87.1 reference Male 89.3 1.23 (1.03 – 1.47) Census Region Northeast 92.2 Midwest 86.7 0.55 (0.44 – 0.70) South 87.7 0.60 (0.47 – 0.76) West 87.4 0.59 (0.42 – 0.81) MSA Urban / suburban 88.8 Rural 85.0 0.71 (0.59 – 0.86) Mother’s marital status Married 88.2 Separated / divorced/ widowed 88.4 1.02 (0.82 – 1.26) Never married 86.1 0.83 (0.54 – 1.27) No parents in household 92.4 1.64 (1.14 – 2.35) Mother’s educational level < High school 87.8 0.88 (0.58 – 1.33) High school graduate 85.8 0.74 (0.60 – 0. 91) > High school 89.1 This slide shows estimated Td/Tdap vaccination coverage by various sociodemographic characteristics. While we looked at a variety of variables, I am only going to show the significant associations today, in the interest of time. As shown, child’s sex, census region, metropolitan statistical area, and mother’s marital status and educational level were all significant predictors of vaccination coverage in bivariate analyses. Female adolescents, teens who lived either outside the Northeast, in a rural area, or in a household without parents, and those whose mother had only a high school education had significantly lower vaccination coverage when compared with the referent group for that particular characteristic. Household income, race/ethnicity, and maternal age were not associated with Td/Tdap vaccination coverage among adolescents.

Estimated Td/Tdap vaccination coverage by health care - related factors Characteristic % UTD Unadjusted OR (95% CI) Identified ≥1 persons as child’s personal doctor or nurse Yes 90.1 1.35 (1.05 – 1.74) No 77.8 reference Preventive health care visit in the past 12 mo 88.5 2.59 (2.11 – 3.18) 85.1 This slide is similar to the previous slide. It shows estimated Td/Tdap vaccination coverage by health care – related factors. Again, I am only showing the variables that were significant in the bivariate analyses. Identification of one or more persons as a teen’s personal doctor or nurse was associated with higher coverage. Vaccination coverage for adolescents who had received preventive health care in the past 12 months was also significantly higher than vaccination coverage for adolescents who did not attend a preventive health care visit in the past 12 months. Insurance type and coverage were not associated with Td/Tdap vaccination coverage among adolescents.

Multivariate Logistic Regression Model Characteristic % UTD * Adjusted OR (95% CI) Child’s age 13 y 81.7 reference 14 y 86.6 1.46 (1.11 – 1.93) 15 y 88.5 1.75 (1.33 – 2.29) 16 y 92.6 2.87 (2.15 – 3.84) 17 y 91.3 2.39 (1.57 – 3.64) Census Region Northeast 92.2 Midwest 87.2 0.56 (0.42 – 0.77) South 87.7 0.59 (0.43 – 0.81) West 87.9 0.60 (0.39 – 0.93) Now I want to move on to the multivariate results. I am only reporting on the variables that made it into the final model. The final multivariate logistic regression model included the following variables: child’s age, census region, metropolitan statistical area, and having a preventive health care visit in the 12 months prior to the interview. Of note, interaction terms were nonsignificant at α = 0.05 and were not included in the final model. The age results for the multivariate analysis are similar to the age results for the bivariate analysis, with coverage increasing as age increases, with the exception of teens aged 17 years. Also similar to the bivariate results, compared with teens living in the Northeast, teens living in other regions were less likely to be reported as vaccinated. * Predictive marginals were used to calculate adjusted vaccination coverage estimates

Multivariate Logistic Regression Model (cont.) Characteristic % UTD* Adjusted OR (95% CI) MSA Urban / suburban 88.8 reference Rural 85.2 0.72 (0.60 – 0.86) Preventive health care visit in the past 12 mo Yes 90.1 2.52 (1.99 – 3.19) No 78.6 Likewise, compared with teens living in urban or suburban areas, teens living in rural areas were less likely to be reported as vaccinated. For adolescents who had a preventive health care visit in the 12 months before the interview date, the odds of having received ≥ 1 dose of Td/Tdap since turning 11 years of age were two and half times the odds for teens who did not attend a preventive health care visit in the year prior to the interview. * Predictive marginals were used to calculate adjusted vaccination coverage estimates

Discussion Multivariate results are consistent with studies of other adolescent vaccines Association between preventive health care visits and provider contact with hepatitis B and meningococcal conjugate vaccine uptake, respectively1,2 The multivariate results are consistent with studies of other adolescent vaccines. Specifically, other studies have demonstrated that preventive health care visits and provider contact have played a role in hepatitis B and meningococcal conjugate vaccine uptake, respectively. Jain N, Hennessey K. Hepatitis B vaccination coverage among U.S. adolescents, National Immunization Survey–Teen, 2006. J Adolesc Health. 2009;44(6):561-7. Lu PJ, Jain N, Cohn AC. Meningococcal conjugate vaccination among adolescents aged 13-17 years, United States, 2007. Vaccine. 2010;28(11):2350-5.

Clinical preventive service guidelines for adolescents ACIP, AMA, AAP, SAM, AAFP: Recommend well child visit for children aged 11–12 years for delivery of preventive services1,2 AMA, AAP, Maternal and Child Health Bureau: Recommend annual well-child visits3 The results of this study and studies of other adolescent vaccines add evidence to support the importance of recommended preventive health care visits in raising vaccination coverage rates. The ACIP and other professional organizations listed on this slide recommend a well child visit for children aged 11–12 years for delivery of preventive services, including vaccinations. The American Medical Association, the American Academy of Pediatrics (AAP), and the Maternal and Child Health Bureau recommend annual well-child visits. CDC. Immunization of adolescents: Recommendations of the Advisory Committee on Immunization Practices, the American Academy of Pediatrics, the American Academy of Family Physicians, and the American Medical Association. MMWR 1996;45(No. RR-13):1-16. Middleman AB, Rosenthal SL, Rickert VI, et al. Adolescent immunizations: A position paper of the Society for Adolescent Medicine. J Adolesc Health 2006;38(3):321–7 Broder KR, Cohn AC, Schwartz B, et al. Adolescent Immunizations and Other Clinical Preventive Services: A Needle and a Hook? Pediatrics. 2008;121:S25-S34. AMA = American Medical Association; AAP = American Academy of Pediatrics; SAM = Society for Adolescent Medicine; AAFP = American Academy of Family Practioners

Td/Tdap vaccine coverage for teens aged 13–17 NSCH NIS –Teen Population Nationally representative Survey administration Random-digit-dialed telephone survey Vaccination status reporting Parental report Provider-verified 2007 uptake estimates 88.2% 72.3% With respect to Td/Tdap vaccine coverage, we are able to compare our findings for Td/Tdap vaccine uptake among 13-17 year olds to estimates from the 2007 National Immunization Survey for Teens (NIS-Teen). Both surveys are similar in population and in survey administration methods. However, the NSCH relies on parental report while vaccination status for the NIS-Teen is provider-verified. As shown in the bottom row of this table, the NSCH estimate is higher than that found in NIS-Teen, perhaps due to parental recall and over-reporting of vaccines received. However, NIS-Teen vaccination histories might not have included all vaccinations received, particularly vaccinations given in settings outside the medical home (e.g., emergency departments). National Immunization Survey. MMWR 2008;57

Limitations Landline telephone survey Potential for nonresponse and noncoverage bias Vaccination history and health care visit data based on parental reports Potential for recall bias Cross-sectional survey No conclusions about causal relationships Unable to assess independent predictors of Tdap (only) vaccination This study is subject to several limitations. First, the NSCH is a landline telephone survey and as such, is subject to error due to nonresponse and noncoverage. However, sampling weights were adjusted to account for potential nonresponse and noncoverage bias, to the extent possible. Second, vaccination history and health care visit data were based on parental reports, not review of medical records, leaving a potential for recall bias. Additionally, the data represent information collected from a cross-sectional survey. Therefore, no conclusions about causal relationships can be made. Finally, independent predictors of receipt of ≥1 dose of Tdap could not be assessed as survey respondents were not specifically asked about the child’s Tdap status.

Conclusions Reported Td/Tdap vaccination coverage among teens aged 13–17 yrs: 88.2% In multivariate analyses: age, MSA, census region, and having a recent preventive health care visit were significantly associated with Td/Tdap vaccination Promoting annual health visits might increase vaccination coverage for Td/Tdap So in conclusion - Overall, reported vaccination coverage with ≥ 1 doses of Td/Tdap was 88.2% (95% CI: 87.2–89.1). In multivariate analyses, age, MSA, census region, and having a recent preventive health care visit were significantly associated with Td/Tdap vaccination. Finally, promoting annual health visits might increase vaccination coverage for Td/Tdap as well as other vaccines. Delivery of other preventive services routinely recommended for adolescents might also improve.

Acknowledgments CDC, NCIRD Robin Curtis, MD, MPH Shannon Stokley, MPH The findings and conclusions in this presentation are those of the authors and do not necessarily represent the official position of the CDC