Paradoxical health care utilization patterns among children in Korea who did not receive mandatory pneumococcal vaccination

Unvaccinated children in the National Immunization Program (NIP) are a public health concern. We used Korean national population data to analyze health care utilization patterns of NIP-eligible children and identify the unvaccinated group.Pneumococcal vaccination (PCV) records were reviewed to determine the vaccination status of children born between 2013 and 2015. Children who received three doses or more from a 3 + 1 schedule were defined as vaccinated, while those who had not received any pneumococcal vaccinations were defined as unvaccinated. Corresponding health care utilization records were retrieved from the National Health Insurance Review and Assessment Service. The incidence of combined pneumococcal infections and health care utilization rates were estimated and the proportion of complementary and alternative medicine (CAM) utilization among the total health care utilization records was measured.In total, 26,893 (2.1%) of 1,272,685 children remained unvaccinated. The incidence of pneumococcal infection was lower in unvaccinated children, at 10.1 cases (9.8–10.3) per 1000 person-months. However, their health care utilization was significantly lower than that noted for vaccinated children (hospital visit rate: 26.6 (95% confidence interval [CI] 26.5–26.7) vs. 3.2 (3.2–3.3) visits annually), indicating underdetection. CAM treatment was sought at least three times often more in unvaccinated children than in vaccinated children (3.5% vs. 1.1%).Unvaccinated children showed significantly lower utilization of overall health care than the vaccinated children; however, a higher preference for CAM was noted among unvaccinated children than among vaccinated children. These differences in care-seeking patterns should be considered when identifying unvaccinated children and providing protection through vaccination programs.