Adverse events following immunization with DTaP-IPV (Tetraxim) in school-aged children in Taiwan, 2017-2020

Vaccination has been an effective method to prevent and control diphtheria, tetanus, pertussis and polio diseases in infancy and adults for years. To maintain the protective effect, a DTaP-IPV vaccine, Tetraxim, was introduced into Taiwan's national immunization program for children at 5 years of age after primary series vaccination in infancy in October 2017 replacing a Tdap-IPV. To survey the safety of this vaccine, data between 01 October 2017 and 31 December 2020 from two surveillance systems, the Vaccine Adverse Events Reporting System (VAERS) and Vaccine Injury Compensation Program (VICP), were reviewed. We analysed patient's demographics, symptoms, time of onset, and outcome. A total of 667,497 doses of DTaP-IPV vaccine were administered during the study period. We combined data from VAERS and VICP and deleted duplicate subjects and reports. There was a total of 59 subjects with AEs and the reporting rate of AEs was 8.8 subjects per 100,000 doses. The most common AEs were injection site erythema and swelling. AEs occurred with a median 1 day after vaccination (range 0-3 days). Among the 59 subjects, eight (13.6 %) with serious AEs were hospitalized. These serious AEs included injection site erythema, swelling or extensive limb swelling after vaccination and hospitalization might have been due to ELS that was misdiagnosed as cellulitis. The national passive surveillance data support the safety profile of Tetraxim as a school-entry booster in children at 5 years old in Taiwan.