Vaccine Congress edition:1st location:Amsterdam, The Netherlands date:9-11 December 2007
Introduction: Few large studies on vaccination coverage in adolescents have been carried out. Timeliness of vaccination and determinants of non- or partial immunization are even less investigated in adolescents.The purpose of this study was to measure coverage in 14-year-old adolescents of Hepatitis B (HBV), Measles-Mumps-Rubella (MMR), and Meningococcus serogroup C (MenC) vaccines administered in Flanders, Belgium.
Methods: 1500 adolescents born in 1991 and living in Flanders were selected with a two-stage-cluster sampling technique. Home visits to document vaccination status and to complete, a questionnaire on sociodemographic indicators and vaccine-related factors were carried out by trained interviewers in 2005 (EPI-survey method). Only documented vaccination dates were accepted. Missing data were, when possible, retrieved through the Flemish school health system.
Results: 1344 adolescents were visited at home. Coverage estimates are shown in table 1.
Table 1: Vaccination coverage per dose in percentage with 95% confidence interval
Dose 1 Dose 2 Dose 3
HBV 83.3 (81.1-85.6) 80.3 (77.9-82.7) 75.7 (73.2-79.2)
MMR 80.6 (78.2-83.0) 83.6 (81.4-85.8)
MenC 79.8 (77.3-82.4)
Only 74.6% of the adolescents had proof of both MMR-vaccines and comparable proportions were completely vaccinated against HBV and MenC. As vaccination data were difficult to obtain, these figures should be seen as absolute minimum coverage rates.Univariate logistic regression showed that lower socioeconomic situation of the parents was instrumental for vaccination status of the adolescent.
Discussion: Previously unreported determinants of lower coverage rates inferred from this study are single divorced parents, larger families (>3 children), lower educational level of adolescent and following special education of staying one year over. Partial employment of the mother resulted in higher adolescent coverage rates. The coverage in adolescents for HBV, MMR and MenC is still below WHO-recommendations in Flanders. Documentation of vaccination data is a major concern. Special attention should be given to adolescents of underprivileged parents.