A 1997 state requirement that all children in Illinois receive the hepatitis B vaccine series in order to enter the fifth grade has not only raised the rate of vaccination to more than 90% in a group of Chicago-area high school students but also has narrowed the vaccination disparity between white students and black or Hispanic students, according to results of a retrospective cohort study.
Ensuring that at least 90% of all students receive the complete vaccine is a goal of the U.S. Department of Health and Human Services Healthy People 2010 program, the authors noted.
The study analyzed vaccination data for the senior class of six Chicago high schools for each of the years 2000–2005.
The six cohorts comprised a total of 106,541 students and included four cohorts who had entered fifth grade before the mandate took effect in October 1997 and two cohorts who had entered fifth grade after the mandate.
In each cohort, 50%–51% were black, 30%–34% were Hispanic, 11%–13% were white, and 5%–6% were Asian American, Dr. Julie Morita of the Chicago Department of Public Health and her colleagues reported (Pediatrics 2008;121:e547–52).
School administrators were permitted to give a 1-year extension to students who had begun the vaccination series, and the investigators wrote that they suspect the mandate was inconsistently enforced, the investigators said.
Still, there was a distinct increase in vaccination coverage after the mandate; the first cohort of students to enter fifth grade after it took effect (that is, in the fall of 1997) had a vaccination coverage level of 38%, compared with 4% for the last group of students to enter fifth grade before the mandate.
By the time this cohort had reached the 12th grade, the coverage rates for white, black, and Hispanic students were 97%, 92%, and 96%, respectively. The rates for the second postmandate cohort were even higher (98%, 96%, and 98%, respectively).
There also was a narrowing of the coverage gap among ethnic groups, even among students who entered fifth grade before the mandate took effect.
Among students who started fifth grade in 1996, 8% of whites, 3% of blacks, and 4% of Hispanics had received the full hepatitis B series by fifth grade.
But by 2000, when that cohort had entered ninth grade, the rate of coverage had risen to 46%, 32%, and 40%, respectively.
This trend was even stronger in the second postmandate cohort; by the time the students who had entered fifth grade in 1998 reached the ninth grade, 93% of whites, 89% of blacks, and 93% of Hispanics were fully vaccinated against hepatitis B.
The investigators did not include vaccination data for Asian American students.
The ninth grade is an important threshold for hepatitis B vaccination, the authors noted, because vaccination by this age “protects most vaccine recipients before the onset of sexual activity, the most common mode of hepatitis B transmission.”
The investigators noted that the demonstrated effectiveness of the Illinois vaccination mandate could be useful to clinicians and legislators seeking to increase coverage rates for other childhood and adolescent vaccinations—particularly the human papillomavirus vaccine, which is also given in a three-dose series.
Dr. Morita and her colleagues noted that, before the mandate took effect, a host of community programs were in place, such as school-based vaccination drives and programs to provide vaccinations to children from low-income families.
In addition, the mandate came 3 years after the American Academy of Pediatrics, the American Academy of Family Physicians, and the Advisory Committee on Immunization Practices recommended routine vaccination of adolescents against hepatitis B.