Comparative Estimation of Coverage between National Immunization Program Vaccines and Non-NIP Vaccines in Korea

This study aimed to describe the differences in vaccination coverage between National Immunization Program (NIP) vaccines and non-NIP vaccines in Korea and to identify factors affecting the difference. Nationwide face-to-face interview-based questionnaire survey among randomly selected 4,374 participants aged 7-83 months was conducted. Vaccination coverage analyzed according to the birth cohorts, geographic areas, and socio-demographic characteristics. We found that NIP vaccines recorded higher primary vaccination coverage compared to non-NIP vaccines (95.9%-100% vs 30.7%-85.4%). The highest rate was Haemophilus influenzae type b (Hib) vaccine (85.4%), which was introduced in 1996, and the lowest rate was rotavirus vaccine (30.7%), which was introduced recently. On multivariate analysis, having a sibling were significantly associated with lower uptake of Hib vaccine, pneumococcal conjugate vaccine (PCV), and rotavirus vaccine; while, older mother's age and attendance to daycare center were significantly associated with lower uptake of PCV and rotavirus vaccine (P < 0.001). We found differences in the vaccine coverage rate between NIP vaccines and non-NIP vaccines; and the data suggests potential disparity in accessing non-NIP vaccines in Korea. Expansion of NIP to include non-NIP vaccines can provide better protection against the diseases through increased coverage.