PhD student Ewha Womans University Seodaemungu, Republic of Korea
Background: Diphtheria-tetanus-acellular pertussis, inactivated poliomyelitis, and Hemophilus influenza type B (DTaP-IPV/Hib) combination vaccine was introduced in the Korean National Immunization Program (NIP) in June 2017.
Objectives: This study was conducted to observe the impact of the introduction of DTaP-IPV/Hib on the vaccination patterns of infants.
Methods: We used the vaccine registry between 2013 and 2020 from Korea Disease Control and Prevention Agency (KCDA) which included data on all the infants who received the NIP vaccines. Among those born between January 1, 2013, and December 31, 2019, all the infants who received DTaP vaccines at least once within 12 months of age were included in the study. We used the two following indicators to assess the impact of DTaP-IPV/Hib combined vaccines. One was the annual complete vaccination rates of DTaP, IPV, and Hib (D-I-H), calculated with the denominator being the number of births. The complete vaccination was defined as the cases when infants complete 3 doses of each D-I-H within 12 months after the birth in compliance with the WHO recommendations. The other was the average number of annual visits to medical institutions for vaccination. To examine the impact of DTaP-IPV/Hib vaccine introduction on vaccination patterns of other vaccines, we classified the infants into two groups, those born in 2013~2017 and 2018~2019. Then we calculated the number of vaccines that the infants receive simultaneously with DTaP and the proportion of the infants by the number of concomitant vaccines that they received with DTaP.
Results: A total of 2,677,801 infants born between 2013 and 2019 were included, of which 51.3% were boys, and 96.7% completed D-I-H doses altogether within 12 months of age. The complete vaccination rate showed an increasing pattern by year, 95.1% in 2013, 96.1% in 2014, 96.5% in 2015, 97.0% in 2016, 97.1% in 2017, and 97.8% both in 2018 and 2019. The average number of vaccination visits showed a declining pattern from 2017, starting from 10.3 in 2013, 2014, and 2015 and 10.9 in 2016, down to 9.6 in 2017, 9.0 in 2018, and 8.8 in 2019. Among the infants who completed D-I-H vaccination, 3 doses per each, 50.9% received up to 5 other vaccines on the same date as the first DTaP dose. The proportion of the infants who received two or more other doses (excluding IPV and Hib) simultaneously with the first DTaP dose was 23.6% among those born in 2013~2017 and 64.0% among those born in 2018~2019.
Conclusions: The introduction of DTaP-IPV/Hib combination vaccine improved complete vaccination rate of D-I-H for infants and reduced the number of visits to medical institutions for vaccination. It also eased the burden of repeated injections, thus increasing the number of other vaccines administered simultaneously with DTaP.
