National, Regional, State, and Selected Local Area Vaccination Coverage Among Adolescents Aged 13–17 Years — United States, 2016

The Advisory Committee on Immunization Practices (ACIP) recommends that adolescents routinely receive tetanus, diphtheria, and acellular pertussis vaccine (Tdap), meningococcal conjugate vaccine (MenACWY), and human papillomavirus (HPV) vaccine (1) at age 11-12 years. ACIP also recommends catch-up vaccination with hepatitis B vaccine, measles, mumps, and rubella (MMR) vaccine, and varicella vaccine for adolescents who are not up to date with childhood vaccinations. ACIP recommends a booster dose of MenACWY at age 16 years (1). In December 2016, ACIP updated HPV vaccine recommendations to include a 2-dose schedule for immunocompetent adolescents initiating the vaccination series before their 15th birthday (2). To estimate adolescent vaccination coverage in the United States, CDC analyzed data from the 2016 National Immunization Survey-Teen (NIS-Teen) for 20,475 adolescents aged 13-17 years.* During 2015-2016, coverage increased for ≥1 dose of Tdap (from 86.4% to 88.0%) and for each HPV vaccine dose (from 56.1% to 60.4% for ≥1 dose). Among adolescents aged 17 years, coverage with ≥2 doses of MenACWY increased from 33.3% to 39.1%. In 2016, 43.4% of adolescents (49.5% of females; 37.5% of males) were up to date with the HPV vaccination series, applying the updated HPV vaccine recommendations retrospectively.† Coverage with ≥1 HPV vaccine dose varied by metropolitan statistical area (MSA) status and was lowest (50.4%) among adolescents living in non-MSA areas and highest (65.9%) among those living in MSA central cities.§ Adolescent vaccination coverage continues to improve overall; however, substantial opportunities exist to further increase HPV-associated cancer prevention.

≥1 HPV vaccine dose varied by metropolitan statistical area (MSA) status and was lowest (50.4%) among adolescents living in non-MSA areas and highest (65.9%) among those living in MSA central cities. § Adolescent vaccination coverage continues to improve overall; however, substantial opportunities exist to further increase HPV-associated cancer prevention.
NIS-Teen is an annual survey that collects data on vaccines received by adolescents aged 13-17 years in the 50 states, the District of Columbia, selected local areas, and territories. ¶ NIS-Teen is conducted among parents and guardians of eligible adolescents identified using a random-digit-dialed sample of landline and cellular telephone numbers.** Parents and guardians are interviewed for information on the sociodemographic characteristics of the adolescent and household, and contact information for the child's vaccination providers. If more than one age-eligible adolescent lives in the household, one adolescent is randomly selected for participation. With parental/ guardian consent, health care providers identified during the interview are mailed a questionnaire requesting the vaccination history from the adolescent's medical record. † † This report presents vaccination coverage estimates for 20,475 adolescents (9,661 females and 10,814 males) aged 13-17 years with adequate provider data. § § NIS-Teen methodology, including methods for weighting and synthesizing provider-reported vaccination histories, has been described (https://www.cdc.gov/ vaccines/imz-managers/nis/downloads/NIS-PUF15-DUG. pdf ). T-tests were used for statistical comparison of weighted data to account for the complex survey design. Weighted linear regression by survey year was used to estimate annual percentage point increases. Differences were considered statistically significant for p-values <0.05.

Vaccination Coverage by Selected Characteristics
Tdap and MenACWY coverage was similar for each age group. For HPV vaccination (≥1-dose, ≥2-dose, and ≥3-dose coverage, and up-to-date status) coverage was higher overall and by sex, for persons aged 17 years (e.g., ≥1-dose coverage was 65.4% versus 53.5% at age 13 years), except for HPV up-to-date status among males, which was highest among males aged 16 years (Table 1). Among adolescents aged 13 years, HPV vaccination coverage was similar for females and males; among adolescents aged 17 years, HPV vaccination coverage was 14-23 percentage points higher among females than among males (Table 1).
Differences in vaccination coverage by race/ethnicity in 2016 were similar to patterns observed in previous years (Supplementary Table 1 (Table 2); however, HPV coverage, overall and by sex, was higher among adolescents living below the federal poverty level than among those living at or above the poverty level (e.g., overall, 12.9 percentage points and 8.4 percentage points higher for ≥1-dose coverage and upto-date status, respectively). HPV coverage, overall and by sex, was 13-17 percentage points lower for adolescents living in non-MSA areas and 5-8 percentage points lower among those living in MSA non-central city areas than among those living in MSA central cities (

Discussion
In 2016, adolescent vaccination coverage in the United States was sustained and continued to improve in several areas: compared with 2015, coverage with Tdap, ≥2 doses of varicella ¶ ¶ Adolescents were classified as below the federal 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. Poverty status was unknown for 724 adolescents. https://www.census.gov/data/tables/time-series/demo/incomepoverty/historical-poverty-thresholds.html. † † ACIP recommends a booster dose at age 16 years. Estimates are provided for ≥2 doses of MenACWY or meningococcal-unknown type vaccine. Calculated only among adolescents who were aged 17 years at time of interview. Does not include adolescents who received 1 dose of MenACWY vaccine at age ≥16 years. § § HPV vaccine, nine-valent (9vHPV), quadrivalent (4vHPV), or bivalent (2vHPV). For ≥1, ≥2, and ≥3 dose measures, percentages are reported among females and males combined (N = 20,475) and for females only (n = 9,661) and males only (n = 10,814). ¶ ¶ Statistically significant difference (p<0.05) in estimated vaccination coverage by age: reference group was adolescents aged 13 years. *** HPV UTD includes those who received ≥3 doses, and those who received 2 doses when the first HPV vaccine dose was initiated before age 15 years and the time between the first and second dose was at least 5 months minus 4 days. † † † By parent/guardian report or provider records.
vaccine, ≥2 doses of MenACWY, and each dose of HPV vaccine increased. Since HPV vaccine was introduced for females in 2006 and for males in 2011, coverage has increased gradually among females and more rapidly among males. During 2015-2016, increases in coverage with each HPV dose, ranging from 3.4 to 6.2 percentage points occurred among males, whereas only a 2.8 percentage point increase in ≥2-dose HPV coverage occurred among females. Coverage with ≥1-dose HPV vaccine among males continues to approach that among females, particularly for adolescents aged 13 years, suggesting that HPV vaccination of both female and male adolescents has been integrated into vaccination practices. Although HPV Abbreviations: ACIP = Advisory Committee on Immunization Practices; APD = adequate provider data; HPV = human papillomavirus; MenACWY = quadrivalent meningococcal conjugate vaccine; Tdap = tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine. * ≥1 dose Tdap at or after age 10 years; ≥1 MenACWY: ≥1 dose MenACWY or meningococcal-unknown type vaccine; ≥2 MenACWY: ≥2 doses MenACWY or meningococcalunknown type vaccine, calculated only among adolescents aged 17 years at time of interview. Does not include adolescents who received their first and only dose of MenACWY at or after age 16 years; HPV vaccine, nine-valent (9vHPV), quadrivalent (4vHPV) or bivalent (2vHPV). ACIP recommends 9vHPV, 4vHPV or 2vHPV for females and 9vHPV or 4vHPV for males. The routine ACIP recommendation was made for females in 2006 and for males in 2011. † NIS-Teen implemented a revised APD definition in 2014, and retrospectively applied the revised APD definition to 2013 data. Estimates using different APD definitions might not be directly comparable.
vaccination initiation (receipt of ≥1 HPV vaccine dose) continues to increase, coverage remains 22-28 percentage points lower than those for Tdap and ≥1-dose MenACWY. These gaps indicate substantial opportunity for improving HPV vaccination practices.
Disparities in adolescent vaccination coverage were found by MSA status: HPV vaccination initiation among adolescents living outside MSA central cities was 16 percentage points lower than among those living in MSA central cities. Although adolescents living in non-MSA areas had substantially lower HPV and MenACWY vaccination coverage compared with those living in MSA central cities, Tdap coverage in these groups was similar. Reasons for these disparities are not well understood. Potential contributing factors might include differences in parental acceptance of certain vaccines and provider participation in, and adolescents' eligibility for, the Vaccines for Children program.*** The disproportionately lower number of pediatric primary care providers found in non-MSA areas than in MSA central city areas (4,5)    Abbreviations: CI = confidence interval; HPV = human papillomavirus; MenACWY = quadrivalent meningococcal conjugate vaccine; MMR = measles, mumps, and rubella; NIS-Teen = National Immunization Survey-Teen; Tdap = tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine; UTD = up to date. * Adolescents (N = 20,475) in the 2016 NIS-Teen were born during January 1998-February 2004. † 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 (https://www.census.gov/data/tables/time-series/demo/incomepoverty/historical-poverty-thresholds.html). Poverty status was unknown for 724 adolescents. § MSA status was determined based on household-reported county of residence, and was grouped into three categories: MSA central city, MSA non-central city, and non-MSA. MSA and central city were as defined by the U.S. Census Bureau (https://www.census.gov/geo/reference/gtc/gtc_cbsa.html). Non-MSA areas include urban populations not located within an MSA as well as completely rural areas. ¶ Estimates with 95% CI half-widths >10 might not be reliable. ** Includes percentages receiving Tdap vaccine at age ≥10 years. † † Includes percentages receiving MenACWY and meningococcal-unknown type vaccine. § § Statistically significant difference (p<0.05) in estimated vaccination coverage by poverty level or metropolitan statistical area; referent groups were adolescents living at or above poverty level and MSA central city, respectively. ¶ ¶ ≥2 doses of MenACWY or meningococcal-unknown type vaccine. Calculated only among adolescents aged 17 years at time of interview. Does not include adolescents who received 1 dose of MenACWY vaccine at age ≥16 years. *** HPV vaccine, nine-valent (9vHPV), quadrivalent (4vHPV), or bivalent (2vHPV). For ≥1-, ≥2-, and ≥3-dose measures, percentages are reported among females and males combined (n = 20,475) and for females only (n = 9,661) and males only (n = 10,814). † † † HPV UTD includes those with ≥3 doses, and those with 2 doses when the first HPV vaccine dose was initiated before age 15 years and time between the first and second dose was at least 5 months minus 4 days. § § § By parent/guardian report or provider records.  this difference in vaccination coverage, because nonpediatric providers might be less familiar with adolescent vaccination recommendations. Because Tdap coverage is substantially higher than ≥1-dose HPV coverage, even in non-MSA areas, lack of access to any vaccination services is unlikely the underlying cause of lower HPV vaccine initiation. A better understanding of reasons for variations in HPV vaccine initiation by MSA status is needed to identify appropriate, targeted strategies to improve HPV vaccination coverage. CDC has published a series of reports in an effort to better understand health disparities between rural and urban areas (https://www.cdc.gov/ ruralhealth/caseforruralhealth.html). Variation in adolescent vaccination coverage among state and local areas might reflect differences in adolescent health care delivery, the prevalence of factors associated with lower vaccination coverage, and immunization program emphasis on, and effectiveness of, adolescent vaccination activities. Immunization programs in several state and local jurisdictions (e.g., Alaska, Maryland, Nevada, New York, and New York City), although not necessarily having the highest HPV vaccination coverage in the nation, have experienced annual increases in coverage that exceed the national average over a 4-year period. Activities contributing to this success, as reported by these immunization programs, include enhancing provider education, assessing vaccination coverage levels in health care provider offices and providing feedback to the practices, conducting media campaigns, engaging community partners, and experiencing a "spillover" effect from middle school vaccination requirements for Tdap and MenACWY vaccines.  5-37.7) 57.3 (53.2-61.2)  41.3 (37.4-45.4) 47.0 (43.3-50.8) 28.9 (25.8-32.3 † † HPV vaccine, nine-valent (9vHPV), quadrivalent (4vHPV), or bivalent (2vHPV). For ≥1-, ≥2-, and ≥3-dose measures, percentages are reported among females and males combined (N = 20,475) and for females only (n = 9,661) and males only (n = 10,814). § § HPV UTD includes those with ≥3 doses, and those with 2 doses when the first HPV vaccine dose was initiated before age 15 years and time between the first and second dose was at least 5 months minus 4 days. ¶ ¶ Statistically significant (p<0.05) percentage point increase from 2015. *** Statistically significant (p<0.05) percentage point decrease from 2015.

TABLE 3. Estimated vaccination coverage with selected vaccines and doses* among adolescents aged 13-17 years, † by HHS region, state, selected local area, or territory -National Immunization Survey-Teen, United States, 2016
† † † Range excludes selected local areas and territories.
At the end of 2016, the recommended HPV vaccination schedule was changed from a 3-dose to a 2-dose series for immunocompetent adolescents initiating the series before their 15th birthday. Three doses are recommended for persons initiating the series at ages 15 through 26 years and for immunocompromised persons (2). The recommendation allows for 1 fewer dose and one fewer visit to a health care provider, which might encourage providers to promote, and parents to accept, vaccination at the recommended age of 11-12 years. Although it is too early to assess the direct impact of the revised recommendation on vaccination practices, when applied retrospectively, the HPV up-to-date coverage was 6.3 percentage points higher than the ≥3-dose HPV coverage. Each year in the United States, an estimated 31,500 newly diagnosed cancers in men and women are attributable to HPV; approximately 90% of these could be prevented by receipt of the nine-valent HPV vaccine (https://www.cdc.gov/cancer/ hpv/statistics/cases.htm). Although it is too early to observe the impact of HPV vaccination on HPV-associated cancers, impact on infection with HPV types targeted by the vaccine and other endpoints have been reported (6)(7)(8). Data from the 2007-2010 National Health and Nutrition Examination Surveys indicate that, compared with 2003-2006 (before HPV vaccine introduction), prevalence of HPV types targeted by the quadrivalent HPV vaccine † † † in cervicovaginal specimens had decreased 56% (from 11.5% to 5.0%) among females aged 14-19 years (6). By 2011-2014, prevalence had declined 71% (from 11.5% to 3.3%) among females aged 14-19 years and 61% (from 18.5% to 7.2%) among females aged 20-24 years (7). Evidence of vaccine impact among males also exists (8).
The findings in this report are subject to at least five limitations. First, the overall household response rate was 32.7% (55.5% for the landline and 29.5% for the cell phone samples), and only 53.9% of landline-completed and 47.4% of cell phone-completed interviews had adequate provider † † † Most HPV vaccine used in the United States before licensure of the ninevalent vaccine at the end of 2014 was quadrivalent HPV vaccine. data. Second, bias in estimates might remain even after adjustment for household and provider nonresponse and phoneless households. ¶ ¶ ¶ Weights have been adjusted for the increasing number of cell phone-only households over time. Nonresponse bias might change, which could affect comparisons of estimates between survey years. Third, estimates stratified by state/local area might be unreliable because of small sample sizes. Fourth, multiple statistical tests were conducted, and a small number might be significant because of chance alone. Finally, ≥2-dose MenACWY coverage likely underestimates the proportion of adolescents who receive ≥2 MenACWY doses. Adolescents might receive a booster dose of MenACWY after age 17 years (1); because NIS-Teen includes adolescents aged 13-17 years, receipt of MenACWY at age ≥18 years cannot be captured in coverage estimates.
Adolescent vaccination coverage can be increased, and the gap between HPV vaccination coverage and coverage with Tdap and ≥1-dose MenACWY can be closed with increased implementation of effective strategies. Providers should use every visit to review vaccination histories, provide strong ¶ ¶ ¶ In a sensitivity analysis of 2012 NIS-Teen data including adjustments for incomplete sample frame, nonresponse bias, and incomplete ascertainment of vaccination status, estimates of Tdap, ≥1-dose meningococcal conjugate, and ≥1-dose HPV vaccination coverage were estimated to be lower than actual values by 1-3 percentage points. https://www.cdc.gov/vaccines/imzmanagers/nis/downloads/NIS-teen-puf15-dug.pdf.