摘要：Objectives. We examined the effect of Michigan’s new school rules and vaccine coadministration on time to completion of all the school-required vaccine series, the individual adolescent vaccines newly required for sixth grade in 2010, and initiation of the human papillomavirus (HPV) vaccine series, which was recommended but not required for girls. Methods. Data were derived from the Michigan Care Improvement Registry, a statewide Immunization Information System. We assessed the immunization status of Michigan children enrolled in sixth grade in 2009 or 2010. We used univariable and multivariable Cox regression models to identify significant associations between each factor and school completeness. Results. Enrollment in sixth grade in 2010 and coadministration of adolescent vaccines at the first adolescent visit were significantly associated with completion of the vaccines required for Michigan’s sixth graders. Children enrolled in sixth grade in 2010 had higher coverage with the newly required adolescent vaccines by age 13 years than did sixth graders in 2009, but there was little difference in the rate of HPV vaccine initiation among girls. Conclusions. Education and outreach efforts, particularly regarding the importance and benefits of coadministration of all recommended vaccines in adolescents, should be directed toward health care providers, parents, and adolescents. Although most vaccine-preventable diseases in the United States are at historically low levels, pertussis, or whooping cough, has steadily increased over the past 20 years. A national epidemic in 2010 resulted in more annual cases than at any time in the previous 60 years, 1 and those numbers were exceeded in 2012, 2 highlighting the continued importance of timely immunization, the need to regularly review updated recommendations, the value of vaccination coverage assessment, and the usefulness of evaluating factors associated with age-appropriate immunization. Vaccines recommended for adolescents aged 11 through 12 years by the Advisory Committee on Immunization Practices (ACIP) in 2010 included a single dose of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) 3 ; a single dose of meningococcal conjugate vaccine (MCV4) 4 ; a 3-dose series of human papillomavirus (HPV) vaccine for girls 5 ; annual seasonal influenza vaccine 6 ; and catch-up of other childhood-recommended vaccines, including varicella. 7 All of these recommendations were of several years’ duration (Tdap 2006; MCV4 2005; HPV [for girls] and varicella catch-up 2007). The National Immunization Survey–Teen 2009 estimated immunization coverage levels for adolescents aged 13 through 17 years nationally and by state. Michigan’s Tdap coverage in this age group was lower than the national average (46.2% vs 55.6%), but otherwise Michigan’s coverage for MCV4 (52.6%), documented varicella history or 2 or more doses of varicella vaccine (74.9%), and 2 or more doses of varicella vaccine in adolescents with no history of disease (47.7%) was comparable to national rates. 8 Vaccine coverage rates for children aged 11 through 12 years have lagged noticeably behind those of older adolescents in Michigan. 9 In January 2010, vaccination levels for Michigan adolescents aged 11 through 12 years were 34.3% for Tdap, 29.0% for MCV4, and 69.3% for history of varicella or 2 or more doses of vaccine 10 —well below Healthy People 2020 goals. 11 Adolescents are challenging to reach because they infrequently present for preventive care, and opportunities for vaccination are often missed at these and at problem-centered visits. 12–14 Concerns related to delivery, consent, and cost exist at the adolescent, parent, and provider level. 14,15 Successful interventions to increase adolescent immunization coverage have involved immunization tracking, telephone or mail reminder or recall, home visits, text message reminders, standing orders, and reinforcement through direct provider recommendation. 16–19 ACIP recommends simultaneous administration (i.e., coadministration) of all needed doses when 2 or more vaccines are indicated, 20 a practice that, if more widely implemented, could dramatically improve coverage in adolescents. 21 School entry laws are another particularly effective strategy to increase vaccination coverage in adolescents. 22,23 New rules for Michigan schools were enacted in January 2010 and became effective in November 2010 24 ; schools were required to report student immunization levels by February 2011. These rules reflected national recommendations and included new requirements for children aged 11 through 18 years who were either starting sixth grade or, if enrolled in a different grade, new entrants to a school district: 1 dose of Tdap if 5 years had elapsed since the last dose of tetanus- and diphtheria-containing vaccine, 1 dose of MCV4, and a catch-up second dose of varicella vaccine or current laboratory evidence of immunity or reliable history of disease. These new requirements were in addition to the vaccines that had been required for sixth-grade entry since 2002: 4 doses of tetanus- and diphtheria-containing vaccine (or 3 doses if the first dose was administered on or after the seventh birthday), 3 doses of polio vaccine, 2 doses of measles-mumps-rubella (MMR) vaccine, 3 doses of hepatitis B vaccine, and 1 dose of varicella vaccine. Like most other states, Michigan allows parents or guardians to waive state-mandated vaccinations for their child for medical or religious reasons. Michigan is also one of only 19 states where parents or guardians may waive state-mandated vaccinations for personal (philosophical) beliefs 25 ; prior to 2010, approximately 3% of Michigan’s sixth graders had 1 or more of the required vaccinations waived annually. 26 We examined school-required and female HPV vaccine coverage in children enrolled in sixth grade in the 2009 or 2010 school year at Michigan schools to determine whether the new sixth-grade requirements for 2010 and vaccine coadministration (i.e., administering more than 1 vaccine at different anatomical sites during the same visit) were associated with completion, and decreased time to completion, of all the required vaccines. We also assessed time to initiation of the HPV vaccine series in girls, a vaccine series that was ACIP recommended but not required under the school rules.
