Vaccination In Korea Research Articles

Accelerated national lot release on COVID-19 vaccines in Republic of Korea

Independent quality testing of samples from vaccine lots is part of quality assurance, especially to ensure the consistency of production lot by lot. Effective national lot release system that ensures the quality of each lot of vaccine before it is on the market is important because vaccines are intended to healthy people. In order to respond more quickly to public health crises such as the COVID-19 pandemic, the MFDS implements accelerated national lot release for rapid vaccination in Republic of Korea.For the accelerated system, improvement has been made in terms of timing of application for lot release and required documents. In addition, the processing period has been shortened and sampling method and test items have been streamlined. A thorough preparation for accelerated lot release has been developed by establishing test methods for a new platform in advance. As a result, a total of 43.88 million doses have been released within eight days on average. The accelerated lot release system has contributed significantly to rapid COVID-19 vaccination in Korea.

Guillain-Barré Syndrome Following the ChAdOx1-S/nCoV-19 Vaccine: A Case Report

Serious neurological complications following coronavirus disease 2019 (COVID-19) vaccination, such as cerebral venous sinus thrombosis or acute disseminated encephalomyelitis, have rarely been reported. Here, we report a case of Guillain-Barré syndrome (GBS) that occurred within 2 weeks of receiving the AstraZeneca ChAdOx1-S/nCoV-19 vaccine. A 61-year-old man presented with weakness and hypesthesia of the legs 9 days after the first dose of the ChAdOx1-S vaccine. The patient progressed to respiratory failure and severe quadriparesis. Nerve conduction studies showed markedly reduced amplitudes of compound muscle action potentials and sensory nerve action potentials in both upper and lower extremities, without definitive evidence of demyelination. The patient was diagnosed with axonal GBS and received intravenous immunoglobulin treatment, with a poor response. This is a rare case of GBS after COVID-19 vaccination in Korea. Physicians should be aware of this rare but serious complication of the COVID-19 vaccine to effectively manage such a situation in clinical practice.

COVID-19 Vaccination in Korea: Past, Present, and the Way Forward.

Since its first emergence in late 2019, severe acute respiratory syndrome coronavirus-2 has claimed more than 6.5 million lives worldwide and continues to infect hundreds of thousands of people daily. To combat this once-in-a-century disaster, several vaccines have been developed at unprecedented speeds. Novel vaccine platforms (messenger ribonucleic acid vaccines and adenoviral vector vaccines) have played a major role in the current pandemic. In Korea, six vaccines, including a domestically developed recombinant vaccine, have been approved. As in other countries, vaccines have been proven to be safe and highly effective in Korea. However, rare serious adverse events and breakthrough infections have undermined public trust in the vaccines, even while the benefits of vaccination far outweigh the risks. The rise of the omicron variant and the subsequent increase in excess mortality demonstrated that while vaccines are a key component of the pandemic response, it alone can fail without non-pharmaceutical interventions like masking and social distancing. The pandemic of coronavirus disease has revealed both the strengths and weaknesses of our healthcare system and pandemic preparedness. When the next pandemic arrives, improved risk communication and vaccine development should be prioritized. To enable timely vaccine development, it is essential to make strategic and sufficient investments in vaccine research and development.

Establishment of the 1st National Reference Standard for Sabin Inactivated Poliomyelitis Vaccine in Korea

In 2019, the first Sabin strain inactivated poliomyelitis vaccine was approved in Korea. It was necessary establishment of national reference standards of that vaccine for consistent quality control and standardization since international standards are provided only in small quantities per year. Therefore, Sabin strain inactivated poliomyelitis vaccine standard candidate was produced in 2019. In this study, we tried to establish the D-antigen content of the candidate standard through collaborate study with five institutions and six laboratories participated in the collaborate research. The candidate standard was set up value of DU/mL with Salk strain International Standard (12/104, NIBSC) and the SDU/mL value was established with the Sabin International Standard (17/160, NIBSC). The D-Ag contents (DU/mL and SDU/mL) derived from each laboratory were calculate using the CombiStat program and analyzed for statistical significance. Earlier this year, the candidate standard was registered as the 1st national reference standard of Sabin strain inactivated poliomyelitis vaccine and the D-Ag contents of the standard was assigned 47, 129, 262 DU/mL and 48, 106, and 193 SDU/mL by ​each type (Type 1, 2, 3,). Because of established of national standard, it will help consistent quality control and standardization of the Sabin strain inactivated poliomyelitis vaccines.

Message Strategies and Viewer Responses: Content Analysis of HPV Vaccination Videos on YouTube

Using content analysis, this study examined the effects of several messaging strategies in YouTube videos promoting human papillomavirus vaccines in Korea. It analyzed a total of 201 videos, focusing on five message strategies—temporal framing, narrative format, gain-loss framing, emotional appeals, and message sensation value. The analysis revealed that the creators of these YouTube videos frequently utilized all of these strategies, except for emotional appeals. It also showed that present-focused framing was effective in eliciting positive responses from viewers, and not including gain-loss framing was more effective in provoking responses. Meanwhile, message sensation values were found to increase both positive and negative viewer responses.

Changes in age-specific seroprevalence of Japanese encephalitis virus and impact of Japanese encephalitis vaccine in Korea.

The Japanese encephalitis (JE) virus is the leading cause of vaccine-preventable encephalitis in Asia. Since the introduction of a universal JE vaccination program and urbanization of Korea, the incidence of JE has dramatically decreased in Korea. However, recent JE cases have occurred, predominantly among unvaccinated adults and with a shift in age distribution. Here we aimed to review the changes in age-specific JE seroprevalence over time and discuss the implications of JE vaccination programs in Korea. Following the last epidemic in 1982–1983, mandatory vaccination for all children aged 3–15 years was conducted annually until 1994. However, JE has reemerged, predominantly affecting unvaccinated adults aged 40 years or older and demonstrating a shift in age distribution toward older populations. The age-specific seroprevalence of the JE virus in Korea has changed noticeably over time. Seropositivity in children and adolescents increased from 10%–59% in the 1970s to 90%–92% in the 1980s after the implementation of the JE vaccination program and increased further to 98% in 2012. No age-specific difference in the seroprevalence of JE was found, and appropriate levels of immunity to JE were maintained for all age groups. Continuous surveillance of the seroprevalence of JE is essential to establish a proper immunization policy in Korea.

COVID-19 Vaccine Perception in South Korea: Web Crawling Approach.

BackgroundThe US Centers for Disease Control and Prevention and the World Health Organization emphasized vaccination against COVID-19 because physical distancing proved inadequate to mitigate death, illness, and massive economic loss.ObjectiveThis study aimed to investigate Korean citizens’ perceptions of vaccines by examining their views on COVID-19 vaccines, their positive and negative perceptions of each vaccine, and ways to enhance policies to increase vaccine acceptance.MethodsThis cross-sectional study analyzed posts on NAVER and Instagram to examine Korean citizens’ perception of COVID-19 vaccines. The keywords searched were “vaccine,” “AstraZeneca,” and “Pfizer.” In total 8100 posts in NAVER and 5291 posts in Instagram were sampled through web crawling. Morphology analysis was performed, overlapping or meaningless words were removed, sentiment analysis was implemented, and 3 public health professionals reviewed the results.ResultsThe findings revealed a negative perception of COVID-19 vaccines; of the words crawled, the proportion of negative words for AstraZeneca was 71.0% (476/670) and for Pfizer was 56.3% (498/885). Among words crawled with “vaccine,” “good” ranked first, with a frequency of 13.43% (312/2323). Meanwhile, “side effect” ranked highest, with a frequency of 29.2% (163/559) for “AstraZeneca,” but 0.6% (4/673) for “Pfizer.” With “vaccine,” positive words were more frequently used, whereas with “AstraZeneca” and “Pfizer” negative words were prevalent.ConclusionsThere is a negative perception of AstraZeneca and Pfizer vaccines in Korea, with 1 in 4 people refusing vaccination. To address this, accurate information needs to be shared about vaccines including AstraZeneca, and the experiences of those vaccinated. Furthermore, government communication about risk management is required to increase the AstraZeneca vaccination rate for herd immunity before the vaccine expires.

The Long-Term Impact of Rotavirus Vaccines in Korea, 2008-2020; Emergence of G8P[8] Strain.

This study evaluated the long-term impact of rotavirus vaccination on prevalence, seasonality, and genotype distribution in Gwangju, Korea for 13 seasons. Rotavirus was identified using ELISA and then sequenced for G and P genotypes by Reverse Transcription Polymerase Chain Reactions for diarrhoeagenic patient specimens from local hospitals between January 2008 and August2020. Of 26,902 fecal samples, 2919 samples (10.9%) were ELISA positive. The prevalence declined from 16.3% in pre-vaccine era to 5.4% in post-vaccine era. In the pre-vaccine period, G1P[8] was the most common genotype, followed by G2P[4], G3P[8], and G9P[8], etc. In the transitional period, the proportion of G2P[4] became the dominant genotype and G1P[8] was still commonly identified. In contrast, the novel genotype G8P[8] was predominant in the post-vaccine period. Meanwhile, G2P[4] and G8P[8] were major genotypes in both Rotarix and RotaTeq groups. The substantial decline of G1P[8] prevalence, reemergence of G1P[8], G3P[8], and G2P[4] rotavirus strains, and surge of the rare G8P[8] after vaccine introduction were interesting points to note. The continuous surveillance on the genotypes of RV will be needed to understand rotavirus epidemiology and their evolutionary patterns, as caution is required when interpreting temporal changes in RV genotype dynamic.

Development of a Potent Stabilizer for Long-Term Storage of Foot-and-Mouth Disease Vaccine Antigens.

A local virus isolate, O/SKR/JC/2014 (O JC), has been considered as a candidate vaccine strain in the development of a domestic foot-and-mouth disease (FMD) vaccine in Korea. However, producing and preserving a sufficient quantity of intact vaccine antigens from the O JC strain was difficult owing to its distinctive structural instability compared to other candidate vaccine strains. Based on this feature, the O JC strain was adopted as a model virus for the stabilization study to determine the optimal stabilizer composition, which enables long-term storage of the FMD vaccine antigen in both aqueous and frozen phases. In contrast to O JC vaccine antigens stored in routinely used Tris-buffered or phosphate-buffered saline, those stored in Tris-KCl buffer showed extended shelf-life at both 4 °C and −70 °C. Additionally, the combined application of 10% sucrose and 5% lactalbumin hydrolysate could protect O JC 146S particles from massive structural breakdown in an aqueous state for up to one year. The stabilizer composition was also effective for other FMDV strains, including serotypes A and Asia 1. With this stabilizer composition, FMD vaccine antigens could be flexibly preserved during the general production process, pending status under refrigeration and banking under ultrafreezing.

Immunogenicity and safety of the third booster dose of the inactivated Japanese encephalitis vaccine in Korean children: A prospective multicenter study

The immunization schedule for the inactivated Japanese encephalitis (JE) vaccine in Korea is a two-dose primary series at 12–24 months of age and three booster doses at 12 months after primary schedule and at 6 and 12 years of age. The aim of this study was to investigate immunogenicity and safety of the third booster dose of the inactivated JE vaccine, as well as the long-term immunogenicity of the second booster dose in Korean children. Healthy children aged 11–13 years, primed and given four doses of inactivated JE vaccines were included. All subjects received the third booster dose of the JE vaccine. Neutralizing antibody (NTAb) titers were assessed before and 4–6 weeks after vaccination using plaque reduction neutralization test (PRNT), and were considered to be protective at ≥ 1:10. Local and systemic adverse events were monitored for 4 weeks after vaccination. Before and after booster vaccination, all seroprotection rates were 100%. Geometric mean titer (GMT) showed a 6.05–fold increase, from 139.11 (95% CI: 110.76, 174.71) to 841.53 (95% CI, 714.25, 991.50). The local tolerability and systemic safety profiles were favorable, with no serious adverse events. In conclusion, the third booster dose of the inactivated JE vaccine was demonstrated to be safe and immunogenic in Korean children when administered according to the current immunization schedule.

Parsonage-Turner Syndrome Following Typhoid Vaccination

Parsonage-Turner syndrome is a rare neurological disease of varying etiology characterized by severe shoulder pain, muscle weakness, and atrophy. Mechanisms are unclear, but are thought to be genetic and immune-mediated reactions. Rarely, Parsonage-Turner syndrome occurs as a side effect of vaccination. A 20-year-old male who worked as a soldier visited the military hospital because of shoulder pain after vaccination against typhoid and was diagnosed with Parsonage-Turner syndrome based on electromyography and joint magnetic resonance imaging. Pain was controlled with a nerve block. Intravenous immunoglobulin was administered for improvement of neurologic symptoms. This case suggests that Parsonage-Turner syndrome should be considered as a side effect of vaccination. To the best of our knowledge, this is the first report of Parsonage-Turner syndrome following vaccination in Korea.

Waning Effectiveness of One-dose Universal Varicella Vaccination in Korea, 2011-2018: a Propensity Score Matched National Population Cohort.

BackgroundDespite high coverage (~98%) of universal varicella vaccination (UVV) in the Republic of Korea since 2005, reduction in the incidence rate of varicella is not obvious. The study aimed to evaluate the vaccine effectiveness (VE) of one-dose UVV by timeline and severity of the disease.MethodsAll children born in Korea in 2011 were included for this retrospective cohort study that analyzed insurance claims data from 2011–2018 and the varicella vaccination records in the immunization registry. Adjusted hazard ratios by Cox proportional hazard models were used to estimate the VE through propensity score matching by the month of birth, sex, healthcare utilization rate, and region.ResultsOf the total 421,070 newborns in the 2011 birth cohort, 13,360 were matched for age, sex, healthcare utilization rate, and region by the propensity score matching method. A total of 55,940 (13.29%) children were diagnosed with varicella, with the incidence rate 24.2 per 1000 person-year; 13.4% of vaccinated children and 10.4% of unvaccinated children. The VE of one-dose UVV against any varicella was 86.1% (95% confidence interval [CI], 81.4–89.5) during the first year after vaccination and 49.9% (95% CI, 43.3–55.7) during the 6-year follow-up period since vaccination, resulting in a 7.2% annual decrease of VE. The overall VE for severe varicella was 66.3%. The VE of two-dose compared to one-dose was 73.4% (95% CI, 72.2–74.6).ConclusionWe found lower long-term VE in one-dose vaccination and waning of effectiveness over time. Longer follow ups of the vaccinated children as well as appropriately designed studies are needed to establish the optimal strategy in preventing varicella in Korea.

Incidence of intussusception before and after the introduction of rotavirus vaccine in Korea.

BackgroundRecent studies have reported that after the introduction of rotavirus vaccine the incidence of intussusception did not change among infants, or slightly increased at the age immediately after the first dose. The rotavirus vaccines were introduced in Korea for private market use in 2007–2008. We investigated the incidence of intussusception before (2002–2006) and after (2009–2015) the vaccine introduction in Korea.MethodsWe conducted an interrupted time series study that used data from the Korean National Health Insurance database to identify infants (<12 months of age) who were diagnosed with intussusception and underwent non-invasive or invasive reduction from 2002 to 2015. According to the recommended ages for immunization, the annual intussusception incidence and the incidence rate ratios were calculated among three age groups, 6–14, 15–24, and 25–34 weeks.ResultsThe annual incidences in infants have decreased over time from 241.7 per 100,000 infants (pre-vaccine period) to 160.1–205.2 per 100,000 infants (post-vaccine period). The incidence rate ratio during the post-vaccine period ranged from 0.66 to 0.85. The incidences of intussusception in all three infant age groups have decreased in post-vaccine period compared to pre-vaccine period (incidence rate ratio range: 0.31–0.65, 0.47–0.75, and 0.68–0.94 in 6–14, 15–24, and 25–34 weeks, respectively).ConclusionsThe incidence of intussusception in infants did not increase after the rotavirus vaccine introduction in Korea, but rather decreased over the past decades. Since the incidence of intussusception varies according to country or region, continuous monitoring the incidence of intussusception in infants is necessary in each county or region.

The Presence of Rabies Virus-Neutralizing Antibody in Wild Boars (Sus scrofa), a Non-Target Bait Vaccine Animal in Korea.

Oral vaccination with bait is an effective method to prevent rabies in wildlife, but non-target wild animals may also ingest the bait vaccine. In Korea, the target animal of the rabies bait vaccine is the raccoon dog (Nyctereutes procyonoides). Bait vaccines have been distributed in Korea for 20 years; although wild raccoon dogs have been tested for antibodies, rabies antibodies have never been investigated in non-target wild animals. Therefore, this study investigated rabies antibody formation in wild boars (Sus scrofa), which is likely the main competitor for the bait vaccine in Korea. In bait areas, 20 of 109 wild boars (18.3%) were seropositive, and 39 of 470 wild boars (8.3%) in non-bait areas were also seropositive. These results provide insights regarding bait uptake or vaccination in non-target wild boars.

Seroprevalence of Neutralizing Antibodies against Japanese Encephalitis Virus among Adolescents and Adults in Korea: A Prospective Multicenter Study.

The immunization schedule for the Japanese encephalitis (JE) vaccine in Korea is a two-dose primary series at 12–24 months of age, followed by booster doses 12 months after the second dose and at the ages of 6 and 12 years. Although the number of JE cases has markedly decreased after the universal vaccination program, JE predominantly occurs in adults. The aim of this study was to assess the age-specific prevalence of the JE-neutralizing antibody (NTAb) among adolescents and adults in Korea. A total of 1603 specimens were collected from a healthy Korean population above 15 years old in five provinces. The JE-NTAb titers were measured with the pseudotyped virus assay and considered to be positive at ≥ 1:50. The seropositivity of JE-NTAb was the highest in the 15–29 years category (>95%) and gradually began to decrease in the age group of 30–44 years (89.42%). The lowest and second lowest JE-NTAb seropositive rates were observed among those aged 70 years or older (59.77%) and those aged 55–59 years (75.24%), respectively. Subjects from Seoul exhibited the highest JE-NTAb titer in all age groups compared to other provinces. In conclusion, the JE-NTAb seropositive rates and titers have maintained appropriate levels in the general Korean population. We propose that adult immunization and boosters at 12 years of age against JE are not strongly recommended in Korea.

Socioeconomic Impact of the Rotavirus Vaccine in Korea

Since the introduction of 2 rotavirus (RV) vaccines in Korea, the vaccination rate has reached over 80% with out-of-pocket spending in the private market. We investigated the socioeconomic impact of RV vaccines in Korea to assess their value and public health contribution. By using National Health Insurance Service claims data, we compared the epidemiologic and economic characteristics of rotavirus gastroenteritis (RVGE) before and after the introduction of RV vaccines. For each year of the study period, the annual prevalence and national costs of RVGE were estimated based on children under 5 years with at least 1 National Health Insurance Service claims record with a diagnosis of RVGE. Compared with the prevaccination period, the prevalence of RVGE decreased in the postvaccination period by 48.9% from 2097 per 100,000 children in 2006 to 1072 per 100,000 children in 2015, implying an increase in the vaccination rate and the prevention effect of the vaccines. The highest reduction was observed among those 12 to <24 months of age (-73.4%), presumably due to the benefit of full vaccination, while children under 2 months, ineligible for the RV vaccine, showed an increase (41.7%). The number of hospitalized RVGE cases per year decreased by 69.0%. The national economic burden of RVGE decreased by 28.6%. The substantial reduction in the socioeconomic burden of RVGE after the introduction of RV vaccines confirms their benefit to society. This study would help health policy makers make empirical decisions on incorporating the vaccination into national immunization programs.

Current use and management of commercial fish vaccines in Korea

The aquaculture industry in Korea has grown rapidly since the 1960s, and it is a major food source. However, the expansion of aquaculture systems has increased the chances of infectious disease outbreaks, and vaccination plays an important role in commercial fish farming. This is the first comprehensive review of commercial fish vaccines in Korea. It not only provides an overview of commercially available fish vaccines and their associated approval processes and laws, but also some perspectives on research advances regarding fish vaccines in Korea. In Korea, fish vaccines are approved only after their safety and effectiveness have been verified according to the Pharmaceutical Affairs Act, and after approval, each vaccine lot must pass the national evaluation criteria. As of the end of 2019, 29 vaccines were approved for 10 fish pathogens, including both single and combination vaccines containing more than two inactivated pathogens. The approved fish vaccines consist of 2 immersion vaccines, as well as 1 intramuscular and 26 intraperitoneal vaccines, which require syringe injection. All the 29 vaccines are manufactured as formalin-inactivated vaccines; 1 is an adjuvant vaccine and 28 are non-adjuvant vaccines; 25 are bacterial vaccines, 2 are viral vaccines, 1 is a parasite vaccine, and 1 is a parasite and bacterial vaccine. In terms of the target fish species, 27 vaccines are used in the olive flounder (Paralichthys olivaceus), 1 in the starry flounder (Platichthys stellatus), and 1 in the red seabream (Pagrus major), striped beakfish (Oplegnathus fasciatus), and amberjack (Seriola quinqueradiata). This imbalance exists mostly because the olive flounder is the main farmed fish species in Korea. In 2018, 67.71 million vaccine doses were distributed following satisfactory performance in the national evaluation. They were used to vaccinate approximately 80.6% of farmed olive flounders.

Carcinogenic risk of human papillomavirus (HPV) genotypes and potential effects of HPV vaccines in Korea

This study investigated the distribution of HPV types in Korean women and evaluated the carcinogenic risk of individual HPV types and the potential effects of HPV vaccines. A total of 4,081 HPV-positive samples between 2014 and 2017 were included. The most prevalent genotypes were HPV 16, 58, 68, and 56. Among them, HPV 16 was significantly higher in high-grade squamous intraepithelial neoplasia or worse (HSIL+ ) group. In cytologically evaluating the risk for HSIL+ by individual HPV types, HPV 16 was associated with the highest risk of HSIL+ (OR = 10.82; 95% CI: 7.93–14.77), followed by HPV 33, 31, 52, 18, 58, 51, and 35, in descending order (OR = 3.50 [type 33] to 2.62 [type 35]). Among those types, HPV 16, 18, 31, 33, and 58 were also significantly associated with HSIL+ on histologic evaluation. The analysis of the HPV subgroups covered by the different vaccines revealed that the HPV types covered by the 9-valent vaccine had a high association with HSIL+ (OR = 4.09; 95% CI: 3.02–5.54). Our findings highlight the different carcinogenic risks posed by the high risk HPV genotypes and the positive potential effects of the 9-valent HPV vaccine in reducing HPV-associated cervical cancer in Korea.

Immunogenicity and safety of a new live attenuated herpes zoster vaccine (NBP608) compared to Zostavax® in healthy adults aged 50 years and older

A multi-centre, randomised, double-blinded, active-controlled, parallel-group clinical trial was carried out to assess the immunogenicity and safety of NBP608—a newly developed live-attenuated zoster vaccine in Korea—relative to Zostavax® in healthy adults aged 50 years or older. Immune responses to the vaccine were evaluated by glycoprotein enzyme-linked immunosorbent assay (gpELISA) and enzyme-linked immunosorbent spot (ELISPOT) assays using the interferon (IFN)-γ and interleukin (IL)-2 FluoroSpot kit 6 weeks after vaccination. Safety was monitored for 26 weeks based on subjects’ diaries, spontaneous reports from subjects, and history taking by the investigators. A total of 845 subjects participated in the screening, and 823 received the vaccination (413 in the NBP608 group and 411 in the comparator group). The gpELISA-determined geometric mean fold rise from baseline to post NBP608 vaccination was 2.75 [95% confidence interval, CI (2.57, 2.94)]. The gpELISA-determined adjusted geometric mean titers (GMTs) of NBP608 and the comparator were 1346.37 [95% CI (1273.99, 1422.87)] and 1674.94 [95% CI (1585.35, 1769.58)], respectively. The adjusted GMT ratio of NBP608 to the comparator was 0.80 [95% CI (0.75, 0.87)]. There was no statistically significant difference between two groups in terms of the geometric mean spot numbers determined by IFN-γ and IL-2 ELISPOT assays at 6 weeks post vaccination (P = 0.7232, 0.3844). The incidence of adverse events (AEs) within 6 weeks post vaccination was 49.82% overall (410/823, 941 cases), 50.73% (209/412, 474 cases) in the NBP608 group, and 48.91% (201/411, 467 cases) in the comparator group. The difference in AE rate between the two groups was not statistically significant (P = 0.6010). Most AEs were mild, with a rate of 83.12% in the NBP608 group and 75.37% in the comparator group. Thus, NBP608 is non-inferior to Zostavax® in terms of inducing the immune response and can be safely administered to adults aged 50 years or older.ClinicalTrials.gov Identifier: NCT03120364.

Development and implementation of standardized method for detecting immunogenicity of acellular pertussis vaccines in Korea.

PurposeThere is no standard method for confirming the immunogenicity of acellular pertussis vaccines. We tried to develop a local standard method for evaluating the immunogenicity of the three-component of acellular pertussis vaccines which was developed by a Korean local company.Materials and MethodsThe developed pertussis antigens (pertussis toxin, filamentous hemagglutinin, pertactin) were evaluated by in-house enzyme-linked immunosorbent assay (ELISA) using 189 negative sera, 25 positive sera, and 73 paired sera (pre- and post-Tdap [tetanus, diphtheria, and acellular pertussis] vaccinated sera). ELISA units were calculated by the reference line method, compared with World Health Organization reference sera, and the cut-off value was calculated using negative sera.ResultsWhen compared to National Institute for Biological Standards and Control control antigen (NIBSC) control antigens, the developed pertussis toxin (PT) and filamentous haemagglutinin (FHA) antigens were 203.48 and 61.60 IU/µg, respectively. Each in-house ELISA was established by validating the coefficients of variation % (PT, 11.53%; FHA, 8.60%; pertactin [PRN], 9.86%) obtained from the results of inter- and intra-assay variation. Also, the cut-off values of PT, FHA, and PRN were 11.65, 38.95, and 5.66 EU/mL, respectively. The distributions of antibody levels in paired showed that 93.15% (68/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were higher than a 100% increase after vaccination. Additionally, the values of 89.04% (65/73) in anti-PT IgG, 97.26% (72/73) in anti-FHA IgG, and 100% in anti-PRN IgG were below each cut-off point.ConclusionWe established an in-house ELISA method using self-developed antigens, and these immunoassays have provided a way to standardize measuring the immunogenicity of newly developed vaccines, through single- and dual-serology.