Establishment of the 2nd National Reference Standard for Diphtheria toxin in Korea

Abstract

ƒThis is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/ license/by-nc/3.0/). The reference standards perform an important role in standardization and consistent quality control of biologicals such as vaccines. The study was aimed to establish the 2nd national standard for diphtheria toxin used in diphtheria potency assay of diphtheria toxoid combined vaccines. The stocks of the first national standard established in 2007 were exhausted, and in 2019, Freeze-dried diphtheria toxin was produced in two lots, 1,962 and 1,942 vials respectively. The feasibility of manufacturing was evaluated through quality evaluation and long-term and accelerated stability tests for candidates. In order to assign the potency of candidate standards, the collaborative study was conducted with five institutions including vaccine manufacturers. The potency of the candidate standards was assigned a value of 210 L+/vial (95% confidence intervalMFDSB-19-002: 208.52~221.58 L+/vial, MFDS-B-19-003: 208.63~219.61 L+/vial). It was confirmed that there was a significant difference in the basic statistics of institutions through One-way ANOVA. But when the post hoc test was conducted to verify the result of ANOVA, not much difference was shown from individual institutions as low variability. Additionally, statistical equivalence was confirmed from institutions. The candidate standard whose quality has been verified will be registered as the second national standard for diphtheria toxin.