Learning Objectives for this Presentation:
By the end of the presentation participants will be able to determine the long-term impact of middle school immunization requirements on adolescent coverage levels.

Background:
In 1999, California legislation required children entering 7th grade to have three doses of hepatitis-B vaccine (HBV) and two doses of measles containing vaccine (MCV). Between 1999 and 2002 compliance rates for 7th grade students in Los Angeles County (LAC) increased from 66.9% to 73.3%. However, six middle schools consistently had low annual 7th grade compliance rates. Twelfth grade students' immunization records were assessed in May 2005 to evaluate long-term follow-up.

Objectives:
To determine HBV and MCV compliance rates among the initial cohort of students affected by the 1999 legislation at 7th and 9th grade entry and at 12th grade completion.

Methods:
HBV and MMR vaccinations dates, gender, race, and ethnicity were recorded for all 12th grade students enrolled in the six high schools receiving students from the six middle schools with low 7th grade compliance rates (lower 10th percentile) from 1999 to 2002. Data were analyzed to determine compliance rates by grade checkpoints and by school site.

Results:
2,815 records were reviewed. Compliance rates for HBV increased from grades 7th to 9th (53% to 80%) and grades 9th to 12th (86%). Similarly, compliance rates for MCV increased from 77% to 84% to 88%, respectively. High schools located in central and south LAC had lower compliance rates (between 57% and 77%) compared to high schools in other areas of LAC (94% and 95%). Poor record keeping, lack of staff time, and lax exclusion policies contributed to lower compliance rates.

Conclusions:
Adolescents affected by the middle school immunization requirement between 1999 and 2002 can remain un-/under-vaccinated even as they advance to high school. High schools in these areas will be targeted to improve immunization coverage levels among this cohort of students.