Vaccination coverage in 14-year-old adolescents: documentation, timeliness, and sociodemographic determinants

The objective of this study was to measure the coverage and influencing determinants of hepatitis B virus, measles-mumps-rubella, and Meningococcus serogroup C vaccination in 14-year-old adolescents in Flanders, Belgium, in 2005.

A total of 1500 adolescents who were born in 1991 and were living in Flanders were selected with a 2-stage cluster sampling technique. Home visits to copy vaccination documents and complete a questionnaire on sociodemographic and other related factors were conducted by trained interviewers. Only documented vaccination dates were accepted. Missing data were, when possible, retrieved through medical charts of the School Health System.

For 1344 (89.6%) adolescents, a home visit was performed. Vaccination coverage was 75.7% for the third dose of hepatitis B virus, 80.6% for the first dose and 83.6% for the second dose of measles-mumps-rubella, and 79.8% for Meningococcus serogroup C. Only 74.6% of the adolescents had proof of 2 measles-mumps-rubella vaccines. Although 1006 (74.8%) adolescents had vaccination data available at home at the time of the interview, only 427 (31.8%) were able to show written proof of all studied vaccines. The probably underestimated coverage rates are well below World Health Organization recommendations, but timeliness of vaccinations was respected. Univariate logistic regression showed that unemployment of the father as proxy measure of socioeconomic status was detrimental for vaccination status, in contrast to partial employment of the mother, which was a favorable factor. Previously unreported determinants of lower coverage rates inferred from this study are single divorced parents, larger families (> or = 4 children), lower adolescent educational level, enrollment in special education, and repeating a grade.

Insufficient documentation is a major barrier in this vaccination coverage study. More attention should go to those with the lowest coverage rates, such as adolescents from large families, with separated parents, and with a lower socioeconomic background.