• IMMUNE NETWORK
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• v.21 no.4
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• pp.29.1-29.9
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• 2021

There are limited data directly comparing humoral and T cell responses to the ChAdOx1 nCoV-19 and BNT162b2 vaccines. We compared Ab and T cell responses after first doses of ChAdOx1 nCoV-19 vs. BNT162b2 vaccines. We enrolled healthcare workers who received ChAdOx1 nCoV-19 or BNT162b2 vaccine in Seoul, Korea. Anti-severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) S1 protein-specific IgG Abs (S1-IgG), neutralizing Abs (NT Abs), and SARS-CoV-2-specific T cell response were evaluated before vaccination and at 1-wk intervals for 3 wks after vaccination. A total of 76 persons, comprising 40 injected with the ChAdOx1 vaccine and 36 injected with the BNT162b2 vaccine, participated in this study. At 3 wks after vaccination, the mean levels (±SD) of S1-IgG and NT Abs in the BNT162b2 participants were significantly higher than in the ChAdOx1 participants (S1-IgG, 14.03±7.20 vs. 6.28±8.87, p<0.0001; NT Ab, 183.1±155.6 vs. 116.6±116.2, p=0.035), respectively. However, the mean values of the T cell responses in the 2 groups were comparable after 2 wks. The humoral immune response after the 1st dose of BNT162b2 developed faster and was stronger than after the 1st dose of ChAdOx1. However, the T cell responses to BNT162b2 and ChAdOx1 were similar.

• Molecules and Cells
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• v.45 no.10
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• pp.738-748
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• 2022

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has posed a serious threat to global public health. A novel vaccine made from messenger RNA (mRNA) has been developed and approved for use at an unprecedented pace. However, an increased risk of myocarditis has been reported after BNT162b2 mRNA vaccination due to unknown causes. In this study, we used single-cell RNA sequencing and single-cell T cell receptor sequencing analyses of peripheral blood mononuclear cells (PBMCs) to describe, for the first time, changes in the peripheral immune landscape of a patient who underwent myocarditis after BNT162b2 vaccination. The greatest changes were observed in the transcriptomic profile of monocytes in terms of the number of differentially expressed genes. When compared to the transcriptome of PBMCs from vaccinated individuals without complications, increased expression levels of IL7R were detected in multiple cell clusters. Overall, results from this study can help advance research into the pathogenesis of BNT162b2-induced myocarditis.

• Clinical and Experimental Vaccine Research
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• v.12 no.4
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• pp.319-327
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• 2023

Purpose: Patients with hematological malignancies are at an increased risk of severe infection with coronavirus disease 2019 (COVID-19). However, developing an adequate immune response after vaccination is difficult, especially in patients with lymphoid neoplasms. Since the long-term effects of the BNT162b2 vaccine are unclear, the humoral immune response 5 months after the two vaccinations in patients with hematological disorders was analyzed. Materials and Methods: Samples were collected from 96 patients vaccinated twice with BNT162b2 and treated with at least one line of an antitumor or immunosuppressive drug in our hospital from November 2021 to February 2022. Serum anti-severe acute respiratory syndrome coronavirus 2 (anti-SARS-CoV-2) spike (S) antibody titers were analyzed. Patients were age- and sex-matched using propensity matching and compared with a healthy control group. Patients with serum anti-SARS-CoV-2 S antibodies were defined as 'responder' if >50 U/mL. The patients had B-cell non-Hodgkin lymphoma (B-NHL), multiple myeloma, chronic myeloid leukemia, etc. Results: Patients had significantly low antibody levels (median, 55.3 U/mL vs. 809.8 U/mL; p<0.001) and a significantly low response rate (p<0.001). Multivariate analysis showed that patients with B-NHL, aged >72 years, were associated with a low response to vaccination. There were no significant differences between patients with chronic myeloid leukemia and healthy controls. Conclusion: Our study shows that patients with hematological disorders are at risk of developing severe COVID-19 infections because of low responsiveness to vaccination. Moreover, the rate of antibody positivity differed between the disease groups. Further studies are warranted to determine an appropriate preventive method for these patients, especially those with B-NHL.

• Clinical and Experimental Vaccine Research
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• v.12 no.2
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• pp.116-120
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• 2023

Purpose: In Japan, the data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibody titers after the booster dose of the coronavirus disease 2019 (COVID-19) vaccine are insufficient. The aim of this study is to evaluate changes in SARS-CoV-2 antibody titers before, 1, 3, and 6 months after the booster dose of the BNT162b2 COVID-19 vaccine among health care workers. Materials and Methods: A total of 268 participants who received the booster dose of the BNT162b2 vaccine were analyzed. SARS-CoV-2 antibody titers were measured before (baseline) and at 1, 3, and 6 months after the booster dose. Factors associated with changes in SARS-CoV-2 antibody titers at 1, 3, and 6 months were analyzed. Cutoff values at baseline were calculated to prevent infection of the omicron variant of COVID-19. Results: The SARS-CoV-2 antibody titers at baseline, and 1, 3, and 6 months were 1,018.3 AU/mL, 21,396.5 AU/mL, 13,704.6 AU/mL, and 8,155.6 AU/mL, respectively. Factors associated with changes in SARS-CoV-2 antibody titers at 1 month were age and SARS-CoV-2 antibody titers at baseline, whereas changes in SARS-CoV-2 antibody titers at 3 and 6 months were associated with the SARS-CoV-2 antibody titers at 1 month. The cutoff values of the SARS-CoV-2 antibody titers at baseline were 515.4 AU/mL and 13,602.7 AU/mL at baseline and 1 month after the booster dose, respectively. Conclusion: This study showed that SARS-CoV-2 antibody titers increase rapidly at 1 month after the booster dose of the BNT162b2 vaccine and begin to decrease from 1 to 6 months. Hence, another booster may be needed as soon as possible to prevent infection.

• Pediatric Infection and Vaccine
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• v.29 no.1
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• pp.28-36
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• 2022

Purpose: To evaluate the efficacy and safety of coronavirus disease 2019 (COVID-19) vaccines in children aged 5-11 years, a rapid systematic review was conducted on published clinical trials of COVID-19 vaccines and studies that analyzed real-world data on adverse events after COVID-19 vaccination. Methods: A systematic search was conducted on medical literature in international (Ovid-MEDLINE) and pre-published literature databases (medRxiv), followed by handsearching up to January 4, 2022. We used terms including COVID-19, severe acute respiratory syndrome coronavirus 2, and vaccines, and the certainty of evidence was graded using the GRADE approach. Results: A total of 1,675 studies were identified, of which five were finally selected. Among the five studies, four consisted of data from clinical trials of each of the four types of COVID-19 vaccines (BNT162b2, mRNA-1273, CoronaVac, and BBIBP-CorV). The remaining study consisted of real-world data on the safety of the BNT162b2 vaccine in children aged 5-11 years. This systematic review identified that COVID-19 vaccines in recipients aged 5-11 years produced a favorable immune response, and were vaccines were effective against COVID-19. The safety findings for the BNT162b2 vaccine in children and early adolescents aged 5-11 years were similar to those data noted in the clinical trial. Conclusions: There is limited data on COVID-19 vaccines in children aged 5-11 years. Consequently continuous and comprehensive monitoring is necessary for the evaluation of the safety and effectiveness of the COVID-19 vaccines.

• Clinical and Experimental Vaccine Research
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• v.13 no.1
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• pp.63-67
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• 2024

This repeated cross-sectional study with two independent sample populations compared the antibody response to severe acute respiratory syndrome coronavirus 2 vaccines in Albania in July-August 2021 and 2022. In 2021, it found higher anti-spike-1 seropositivity and antibody levels in fully vaccinated individuals, especially with BNT162b2 and ChAdOx1 and to a lesser degree with CoronaVac. By 2022, all single-dose recipients showed high antibody responses, suggesting natural infection-enhanced immunity. The study indicates a significant evolution in the antibody response to different coronavirus disease 2019 vaccines and suggests that a single vaccine dose, coupled with natural infection, might suffice to maintain adequate immunity levels in an endemic scenario.

• IMMUNE NETWORK
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• v.22 no.3
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• pp.24.1-24.12
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• 2022

Coronavirus disease 2019 (COVID-19) vaccination in immunocompromised, especially transplant recipients, may induce a weaker immune response. But there are limited data on the immune response after COVID-19 vaccination in liver transplant (LT) recipients, especially on the comparison of Ab responses after different vaccine platforms between mRNA and adenoviral vector vaccines. Thus, we conducted a prospective study on LT recipients who received two doses of the ChAdOx1 nCoV-19 (ChAdOx1), mRNA-1273, or BNT162b2 vaccines compared with healthy healthcare workers (HCWs). SARS-CoV-2 S1-specific IgG Ab titers were measured using ELISA. Overall, 89 LT recipients (ChAdOx1, n=16 [18%]) or mRNA vaccines (mRNA-1273 vaccine, n=23 [26%]; BNT162b2 vaccine, n=50 [56%]) received 3 different vaccines. Of them, 16 (18%) had a positive Ab response after one dose of COVID-19 vaccine and 62 (73%) after 2 doses. However, the median Ab titer after two doses of mRNA vaccines was significantly higher (44.6 IU/ml) than after two doses of ChAdOx1 (19.2 IU/ml, p=0.04). The longer time interval from transplantation was significantly associated with high Ab titers after two doses of vaccine (p=0.003). However, mycophenolic acid use was not associated with Ab titers (p=0.53). In conclusion, about 3-quarters of LT recipients had a positive Ab response after 2 doses of vaccine, and the mRNA vaccines induced higher Ab responses than the ChAdOx1 vaccine.

• IMMUNE NETWORK
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• v.21 no.6
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• pp.41.1-41.13
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• 2021

Correlation between vaccine reactogenicity and immunogenicity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. Thus, we investigated to determine whether the reactogenicity after coronavirus disease 2019 vaccination is associated with antibody (Ab) titers and T cell responses. This study was prospective cohort study done with 131 healthcare workers at tertiary center in Seoul, South Korea. The degrees of the local reactions after the 1st and 2nd doses of ChAdOx1 nCov-19 (ChAdOx1) vaccination were significantly associated with the S1-specific IgG Ab titers (p=0.003 and 0.01, respectively) and neutralizing Ab (p=0.04 and 0.10, respectively) in age- and sex-adjusted multivariate analysis, whereas those after the BNT162b2 vaccination did not show significant associations. T cell responses did not show significant associations with the degree of reactogenicity after the ChAdOx1 vaccination or the BNT162b2 vaccination. Thus, high degree of local reactogenicity after the ChAdOx1 vaccine may be used as an indicator of strong humoral immune responses against SARS-CoV-2.

• Clinical and Experimental Vaccine Research
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• v.12 no.1
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• pp.60-69
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• 2023

Purpose: Although the fast development of safe and effective messenger RNA (mRNA) vaccines against severe acute respiratory syndrome coronavirus 2 has been a success, waning humoral immunity has led to the recommendation of booster immunization. However, knowledge of the humoral immune response to different booster strategies and the association with adverse reactions is limited. Materials and Methods: We investigated adverse reactions and anti-spike protein immunoglobulin G (IgG) concentrations among health care workers who received primary immunization with mRNA-1273 and booster immunization with mRNA-1273 or BNT162b2. Results: Adverse reactions were reported by 85.1% after the first dose, 94.7% after the second dose, 87.5% after a third dose of BNT162b2, and 86.0% after a third dose of mRNA-1273. They lasted for a median of 1.8, 2.0, 2.5, and 1.8 days, respectively; 6.4%, 43.6%, and 21.0% of the participants were unable to work after the first, second, and third vaccination, respectively, which should be considered when scheduling vaccinations among essential workers. Booster immunization induced a 13.75-fold (interquartile range, 9.30-24.47) increase of anti-spike protein IgG concentrations with significantly higher concentrations after homologous compared to heterologous vaccination. We found an association between fever, chills, and arthralgia after the second vaccination and anti-spike protein IgG concentrations indicating a linkage between adverse reactions, inflammation, and humoral immune response. Conclusion: Further investigations should focus on the possible advantages of homologous and heterologous booster vaccinations and their capability of stimulating memory B-cells. Additionally, understanding inflammatory processes induced by mRNA vaccines might help to improve reactogenicity while maintaining immunogenicity and efficacy.

• IMMUNE NETWORK
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• v.22 no.4
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• pp.31.1-31.3
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• 2022