Danish MMR vaccination coverage is considerably higher than reported

Area of Science:

• Pediatrics
• Public Health
• Immunization Practices

Background:

• The Danish national registers indicate a significant number of unvaccinated children despite the established measles, mumps, and rubella (MMR) vaccination program.
• Discrepancies in vaccination status reporting may impact public health assessments and interventions.

Purpose of the Study:

• To accurately estimate the first dose measles, mumps, and rubella (MMR1) vaccination coverage in Danish children.
• To investigate the reliability of national register data versus medical record reviews for vaccination status.

Main Methods:

• A cross-sectional study involving 1,712 children aged 18-42 months across 19 general practices in the Central Denmark Region.
• Validation of vaccination status through medical record review for children identified with negative MMR1 status in register-based data.

Main Results:

• Medical record review indicated 94% MMR1 vaccination coverage, compared to 86% in register-based data.
• Of 246 children recorded as unvaccinated, 55% had received the MMR1 vaccine according to their medical records.
• Discrepancies were primarily attributed to administrative reimbursement errors.

Conclusions:

• Actual MMR1 vaccination coverage in Denmark is likely higher than national registers report.
• Medical record review is a crucial method for verifying vaccination status and correcting discrepancies in registry data.