Cohort Strengths and Limitations

Maternal linkage for about 78% of children enables analysis of prenatal exposures. The cohort's large scale allows more precise association estimates than many previous studies and enables analysis of rare childhood cancer sites and specific vaccine types. Long follow-up of up to 18 years supports detection of cancers in later childhood and adolescence. Vaccination assessment before 2008 is incomplete because standardised nationwide billing codes were not fully implemented. Private health insurance data are absent and the AOK-insured population is under-represented. ICD-10 cancer codes provide limited detail about histology and molecular cancer characteristics.