Changes in vaccination practices among infants after the introduction of DTaP-IPV/Hib combination vaccines

Hee-Jin Kim; Suvin Park; Na-Young Jeong; Nam-Kyong Choi

doi:10.1016/j.jvacx.2024.100484

Changes in vaccination practices among infants after the introduction of DTaP-IPV/Hib combination vaccines

Vaccine X. 2024 Apr 9:18:100484. doi: 10.1016/j.jvacx.2024.100484. eCollection 2024 Jun.

Authors

Hee-Jin Kim¹, Suvin Park¹, Na-Young Jeong¹, Nam-Kyong Choi^{1

2}

Affiliations

¹ Department of Health Convergence, Ewha Womans University, Seoul, Republic of Korea.
² Graduate School of Industrial Pharmaceutical Science, College of Pharmacy, Ewha Womans University, Seoul, Republic of Korea.

Abstract

Background: Diphtheria-tetanus-acellular pertussis, polio, and Haemophilus influenza type B (DTaP-IPV/Hib) combination vaccine was introduced as a part of the Korea National Immunization Program (NIP) on June 19, 2017. Combination vaccines can improve vaccination rates by simplifying the vaccination schedule.

Objective: To explain how the introduction of DTaP-IPV/Hib in the NIP has changed vaccination practices for infants.

Methods: Using a nationwide vaccine registry, the proportion of infants who completed the full recommended doses of the primary series of DTaP, IPV, and Hib (D-I-H) within 12 months of age was estimated among those born between 2013 and 2019. Among those, the proportions of those who received the same DTaP components for all 3 doses during the primary series were calculated for the 2013-2016 and the 2017-2019 birth cohorts. Those who received the same component of DTaP throughout the entire primary vaccination schedule were categorized into 3 groups by DTaP components to compare the average frequency of medical visits for vaccination.

Results: A total of 2,703,822 infants were born between 2013 and 2019, of which 96.7% completed full doses of the primary D-I-H series within 12 months of age. For the 2013-2016 birth cohorts, most received DTaP-IPV-only (75.4%), while most of the 2017-2019 birth cohorts received DTaP-IPV/Hib-only (81.0%) to complete the 3 doses for primary D-I-H series. The average frequency of medical visits for vaccination showed a significant difference across the 3 groups classified by DTaP components in every birth cohort (p < 0.001).

Conclusions: After the introduction of DTaP-IPV/Hib, most infants completed the primary D-I-H series with the combination vaccine and there was a significant reduction in the average number of medical visits for vaccination. Our findings provide important insights for countries considering the introduction of combination vaccines into their NIP.

Keywords: Combination vaccine; DTaP-IPV/Hib vaccine; Infants; National immunization program; Vaccination coverages; Vaccination patterns.