National, State, and Local Area Vaccination Coverage Among Adolescents Aged 13--17 Years --- United States, 2008

National, State, and Local Area Vaccination Coverage Among Adolescents Aged 13--17 Years --- United States, 2008

In recent years, the Advisory Committee on Immunization Practices (ACIP) has recommended three newly licensed vaccines: meningococcal conjugate vaccine (MCV4; 1 dose); tetanus, diphtheria, acellular pertussis vaccine (Tdap; 1 dose); and (for girls) quadrivalent human papillomavirus vaccine (HPV4; 3 doses) (1). ACIP also recommends that adolescents receive recommended vaccinations that were missed during childhood: measles, mumps, rubella vaccine (MMR; 2 doses); hepatitis B vaccine (HepB; 3 doses); and varicella vaccine (VAR; 2 doses) (1). Since 2006, CDC has conducted the National Immunization Survey--Teen (NIS-Teen) to estimate vaccination coverage from a national sample of adolescents aged 13--17 years (2). This report summarizes results from the 2008 NIS-Teen and, for the first time, includes estimates for each of the 50 states and selected local areas. Nationally, vaccination coverage for the three most recently recommended adolescent vaccinations and one childhood vaccination increased from 2007 to 2008: MCV4 (from 32.4% to 41.8%), Tdap (from 30.4% to 40.8%), ≥1 dose of HPV4 (from 25.1% to 37.2%), and ≥2 doses of VAR among those without disease history (from 18.8% to 34.1%). However, substantial variability in vaccination coverage was observed in 2008 among state and local areas and by race/ethnicity and poverty status. For the first time, the Healthy People 2010 target of 90% coverage among adolescents aged 13--15 years was met for MMR and HepB. Public health agencies should continue annual monitoring of adolescent vaccination coverage levels to identify trends and differences by geographic area, race/ethnicity, and poverty status.

NIS-Teen collects vaccination information on adolescents aged 13--17 years* in the 50 states and selected local areas† using a random-digit--dialed sample of household telephone numbers. After parents/guardians grant permission, surveys are mailed to all of the adolescents' vaccination providers identified by the parents/guardians to obtain vaccination histories (2). During 2008, NIS-Teen was expanded; the survey was administered over four quarters compared with only the fourth quarter in 2006 and 2007 (2,3), and the analytic sample size increased nearly fivefold from 2006 and 2007 (2,3). For 2008 NIS-Teen, the household response rate§ was 58.7%; a total of 17,835 adolescents with provider-verified vaccination records were included in this report. A description of NIS-Teen methods and survey content has been published (2). Statistical differences in vaccination coverage were evaluated using chi square and t-tests and were considered statistically significant at p<0.05.

Among adolescents aged 13--17 years, vaccination coverage with ≥1 dose of tetanus, diphtheria toxoid vaccine (Td) or Tdap after age 10 years remained stable at 72.2%; however, coverage with ≥1 dose of Tdap increased from 30.4% in 2007 to 40.8% in 2008 (Table 1). Vaccination coverage with ≥1 dose of MCV4 increased from 32.4% in 2007 to 41.8% in 2008. For HPV4, 37.2% of adolescent females had initiated the vaccination series (≥1 dose) in 2008, compared with 25.1% in 2007, and 17.9% of females had received ≥3 doses. Among adolescent females who initiated the HPV4 series, 79.4% had received their first dose at least 24 weeks before the interview date (the minimum period in which to complete the series) (4); of these, 59.6% (95% confidence interval [CI] = 55.5--63.5) had received ≥3 doses.

Vaccination coverage with ≥2 doses of MMR and ≥3 doses of HepB remained steady compared with 2007 (Table 1). Fewer adolescents had a reported history of varicella disease in 2008 (59.8%) compared with 2007 (65.8%), and more adolescents had received ≥1 dose and ≥2 doses of VAR (Table 1).

Substantial differences were observed in vaccination coverage estimates among states and local areas (Table 2). Three states (Arizona, New Hampshire, and New York) had coverage of >50% for all three vaccines routinely recommended for adolescents (Tdap, MCV4, and HPV4). Other states with coverage >50% for at least one of the three vaccines, including Colorado, New Mexico, Pennsylvania, and Wisconsin (≥1 dose of Tdap); Delaware, District of Columbia, Louisiana, Maryland, Massachusetts, New Jersey, Pennsylvania, Rhode Island, and Wisconsin (≥1 dose of MCV4); and Massachusetts, Rhode Island, and Vermont (≥1 dose of HPV4).

Variability in coverage was observed among racial/ethnic¶ groups and by poverty status** (Table 3). Blacks (87.9%) had lower vaccination coverage percentages than whites (93.7%) for protection against varicella (i.e., history of varicella disease or ≥1 dose of VAR) and Tdap (36.0% versus 41.7%). Overall, the percentage of adolescents with history of varicella or ≥1 dose of VAR was lower for those living below the poverty level (88.9%) compared with children at or above poverty (93.5%). Compared with whites, coverage was higher among American Indian/Alaska Natives for MMR (93.9% versus 89.9%) and Td/Tdap (81.4% versus 71.6%). Coverage also was higher among Hispanics than whites for ≥1 dose of MCV4 (46.8% versus 39.7%) and ≥1 dose of HPV4 (44.4% versus 35.0%). Adolescent females living below the poverty level had a higher vaccination coverage percentage for ≥1 dose of HPV4 (46.4%) than adolescent females living at or above the poverty level (35.8%).

Healthy People 2010 established vaccination coverage targets of 90% for adolescents aged 13--15 years for ≥3 doses of HepB, ≥2 doses of MMR, ≥1 dose of Td or Tdap, and ≥1 dose of VAR, among those without history of disease (5). For the first time, Healthy People 2010 targets were achieved for ≥3 doses of HepB (91.8%, CI = 90.7--92.8) and ≥2 doses of MMR (90.7%, CI = 89.6--91.8). Vaccination coverage remained stable at 70.7% (CI = 69.0--72.4) for ≥1 dose of Td or Tdap, and increased from 80.2% in 2007 to 85.5% (CI = 83.5--87.3) in 2008 for ≥1 dose of VAR.

Reported by: S Stokley, MPH, C Dorell, MD, D Yankey, MS, Immunization Svc Div, National Center for Immunization and Respiratory Diseases, CDC.

Editorial Note:
This is the third annual report of national adolescent vaccination coverage based on provider-reported vaccination histories from NIS-Teen and the first report of state and local area estimates. Coverage levels for vaccines routinely recommended for adolescents continued to increase nationally; however, coverage varied substantially among state and local areas. Differences also were observed by race/ethnicity and poverty status including higher HPV4 (≥1 dose) coverage among Hispanic females compared with whites and among adolescents living below compared with those living at or above the poverty level.

The wide variation in adolescent coverage levels among states might be the result of changes in immunization policies, recent experiences with outbreaks of vaccine preventable diseases, or efforts to remove cost as a barrier to vaccination. For example, Colorado, a state with high Tdap coverage, implemented a Tdap requirement for 6th and 10th grade students during the 2007--08 school year, incrementally increasing the grades covered until 2011, when the requirement will apply to all students in grades 6--12 (J. Reynolds, Colorado Immunization Program, personal communication, 2009). During the 2007--08 school year, 22 states reported having a requirement for a tetanus-containing vaccine for entry into middle school (only seven specified Tdap formulation); no states reported requirements for MCV4 or HPV4 vaccines.†† In New Hampshire, an increase in funds contributed by insurance companies for state purchase of vaccine soon after HPV4 was recommended allowed the state to provide universal coverage to females aged 11--18 years (M. Bobinsky, New Hampshire Immunization Program, personal communication, 2009). However, in 2008, only seven states provided universal coverage of all routinely recommended pediatric vaccines for all children.§§ Further evaluation of NIS-Teen data is needed to assess the impact state middle school requirements and vaccine-financing policies have on adolescent vaccination coverage.

Among vaccines routinely recommended for adolescents, coverage with ≥1 dose of HPV4, which was approved only 2 years before the survey, had the greatest percentage-point increase (12.1) in vaccination coverage from 2007 to 2008. The percentage of females initiating the HPV4 series was 9.4 percentage points higher among Hispanics compared with whites and 10.6 percentage points higher among those who live below the poverty level than those who live at or above the poverty level. These findings are important because certain HPV infections are a major cause of cervical cancer and Hispanic adult females and those who live below the poverty level tend to have lower cervical cancer screening rates and higher rates of cervical cancer incidence and mortality (4).

Why HPV4 vaccination coverage was higher among Hispanic adolescent females than whites was not clear. However, among survey participants, a much greater percentage of Hispanic adolescents were living below the poverty level (43.2%) than whites (6.7%). Higher coverage for the first dose of HPV4 among adolescents living below the poverty level might be explained by vaccine financing concerns. Because HPV4 is the most expensive vaccine recommended for adolescents (6), its availability through the Vaccines for Children (VFC) program has removed cost as a barrier to receiving HPV4 among VFC-eligible adolescents (i.e., adolescents who are uninsured, Medicaid eligible, or of American Indian/Alaska Native descent). Financial barriers to purchasing and administering HPV4 vaccine have been reported among private health-care providers (7), which might account for the lower coverage observed among adolescents who live at or above the poverty line and are more likely to be privately insured. Differences by poverty status were not observed for 3-dose HPV4 coverage; however, coverage overall was low (17.9%). Barriers other than cost might affect the ability of adolescent females to complete the HPV4 series, and further studies are needed to understand and address the barriers to receiving all of the recommended doses of HPV4.

The findings in this report are subject to at least four limitations. First, NIS-Teen is a landline telephone survey; although studies indicate that statistical adjustments adequately compensate for exclusion of households without telephones (8), sampling bias might remain. Second, underestimates of vaccination coverage might have resulted from the exclusive use of provider-verified vaccination histories because completeness of these records is unknown. Third, sample sizes were insufficient to adequately compare vaccine coverage rates among racial/ethnic groups stratified by poverty status. Finally, annual estimates for state and local areas and by racial/ethnic groups should be interpreted with caution because of smaller sample sizes and wider confidence intervals.

CDC will continue to monitor vaccination coverage among adolescents annually, enabling further analysis of coverage trends by race/ethnicity, poverty status, and geographic area. Results from a systematic review in 2000 identified several strategies shown to improve vaccination coverage among children, adolescents, and adults, including 1) client and provider reminder, 2) vaccination requirements for school attendance, 3) reduction of out-of-pocket costs, 4) increased vaccination access in health-care settings, and 5) assessment and feedback to vaccination providers (9). The majority of studies from which these efforts were identified targeted infant vaccination; therefore, additional research to identify evidence-based strategies for improving vaccination coverage among adolescents specifically will be needed to achieve high coverage levels in this population.

References
CDC. Recommended immunization schedules for persons aged 0--18 years---United States. 2009. MMWR 2008;57(51&52).
Jain N, Singleton JA, Montgomery M, Skalland B. Determining accurate vaccination coverage rates for adolescents: the National Immunization Survey-Teen 2006. Public Health Rep 2009;124:642--51.
CDC. Vaccination coverage among adolescents aged 13--17 years---United States, 2007. MMWR 2008;57:1100--3.
CDC. Quadrivalent human papillomavirus vaccine. Recommendations of the Advisory Committee on Immunization Practices (ACIP). MMWR 2007;56(No. RR-2).
US Department of Health and Human Services. Objective 14-27: increase routine vaccination coverage levels for adolescents. Healthy people 2010 (conference ed, in 2 vols). Washington, DC: US Department of Health and Human Services; 2000. Available at http://www.healthypeople.gov/document/html/objectives/14-27.htm.
CDC. CDC vaccine price list. September 2, 2009. Available at http://www.cdc.gov/vaccines/programs/vfc/cdc-vac-price-list.htm.
Freed GL, Cowan AE, Clark SJ. Primary care physician perspectives on reimbursement for childhood immunizations. Pediatrics 2008;122:1319--24.
Molinari N, Wolter KM, Skalland B, et al. Quantifying bias in a health survey: an application of total survey error modeling to the National Immunization Survey. Presented at the annual meeting of the American Association for Public Opinion Research, May 14--17, 2009, Hollywood, FL.
Briss PA, Rodewald LE, Hinman AR, et al. Reviews of evidence regarding interventions to improve vaccination coverage in children, adolescents, and adults. The Task Force on Community Preventive Services. Am J Prev Med 2000;18(1 suppl):97--140.
* Eligible participants were born during January 1990--February 1996.

† Six local areas that received federal immunization grants were sampled separately: District of Columbia; Chicago, Illinois; New York, New York; Philadelphia County, Pennsylvania; Bexar County, Texas; and Houston, Texas.

§ The Council of American Survey Research Organizations (CASRO) household response rate is the product of the resolution rate (82.2%), screening completion rate (83.8%), and interview completion rate (85.2%).

¶ Respondents who self-identified as white, black, Asian, or American Indian/Alaska Native were all considered non-Hispanic. Persons who self-identified as Hispanic might be of any race.

** Adolescents were classified as below poverty level if their total family income was less than the federal poverty level specified for the applicable family size and number of children aged <18 years. All others were classified as at or above the poverty level. Additional information is available at http://www.census.gov/hhes/www/poverty.html. Poverty status was unknown for 744 adolescents.

†† Additional information available at http://www2a.cdc.gov/nip/schoolsurv/combinedlaws2007.pdf.

§§ Additional information available at http://www.cdc.gov/vaccines/programs/vfc/projects/data/vacc-supply-public-2008.htm.

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National, State, and Local Area Vaccination Coverage Among Adolescents Aged 13--17 Years --- United States, 2008