Analysis of Vaccinations Outside the National Immunization Program in South Korea

Although South Korea’s National Immunization Program (NIP) currently supports 19 vaccines, substantial vaccination demand may exist outside the populations and vaccines covered by the program. This study quantified vaccination demand outside the NIP to provide evidence for future expansion of national immunization policies. We analyzed annual NIP vaccination records from the Korea Disease Control and Prevention Agency and vaccine supply data from the Health Insurance Review and Assessment Service for 2018-2022. Ten vaccines against eight infectious diseases were included. Non NIP vaccination demand was operationally estimated as vaccine supply to medical institutions, excluding returns and disposal, minus vaccinations administered through the NIP. Demand was assessed in terms of volume, expenditure, and proportion of total vaccine supply. Vaccine supply distributions by medical institution type and region were also examined. In 2022, substantial non NIP demand was observed even for NIP-covered vaccines, including tetanus-diphtheria (86.9%), tetanus-diphtheria-acellular pertussis (76.9%), varicella (45.8%), and influenza (40.9%) vaccines. The largest non-NIP vaccination volume was observed for influenza vaccine (8.25 million doses), while the highest expenditure was for the 9-valent human papillomavirus vaccine (KRW 119 billion), followed by influenza vaccine (KRW 106 billion). Vaccine supply was concentrated in primary care institutions and the capital area. Considerable vaccination demand exists outside the current NIP coverage in South Korea, including for vaccines already included in the program. These findings provide quantitative evidence to support decisions regarding expansion of eligible populations, introduction of additional vaccines, and evaluation of regional equity in vaccine access.