1.Maternal Exposures to COVID-19 Vaccine and Adverse Birth Outcomes:National Population Study in Korea
Kyuwon KIM ; Erdenetuya BOLORMAA ; Eunseon GWAK ; Ju-Young SHIN ; Nam-Kyong CHOI ; Young June CHOE ; Seung-Ah CHOE
Journal of Korean Medical Science 2025;40(17):e63-
Background:
This study aimed to estimate the association between mRNA coronavirus disease 2019 (COVID-19) vaccine exposure during pregnancy and the risks of preterm birth and congenital malformations leveraging a national population data.
Methods:
This retrospective cohort study utilized national data from the National Health Insurance System, linking maternal and infant records with COVID-19 vaccination registries.Newborns with congenital malformations were identified using diagnosis codes. The analysis included women aged 20–49 who gave live births between February 2022 and December 2022. Odds ratios (ORs) for preterm birth and any congenital malformation per COVID-19 vaccination during pregnancy compared to 1:4 matched unvaccinated controls, adjusted for maternal age, residential area, employment, income, disability, month of conception, prepregnancy obesity, smoking, and severe acute respiratory syndrome coronavirus 2 infection prior to pregnancy, were calculated. We compared the risk of two outcomes between BNT162b2 and mRNA-1273.
Results:
Among 106,692 women who gave birth during the study period, 8,966 (8.4%) received a COVID-19 vaccination during pregnancy. Of the newborns, 7,039 (6.6%) were preterm births and 7,658 (7.2%) had congenital malformations. COVID-19 vaccination during pregnancy was associated with a comparable risk of preterm birth (OR, 1.03; 95% confidence interval [CI], 0.77–1.36) and a similar risk of congenital malformations (0.90; 95% CI, 0.72–1.12) compared to non-vaccinees. The ORs of preterm birth (1.02; 95% CI, 0.77–1.36) and congenital malformation (0.91; 95% CI, 0.73–1.14) for mRNA-1273 were comparable to those for BNT162b2.
Conclusion
COVID-19 vaccines during pregnancy poses no increased risk of preterm birth and congenital malformations compared to those not exposed to the vaccine, with similar risk levels observed between the two mRNA vaccines. This finding provides additional evidence supporting the safety of COVID-19 vaccines.
2.Maternal Exposures to COVID-19 Vaccine and Adverse Birth Outcomes:National Population Study in Korea
Kyuwon KIM ; Erdenetuya BOLORMAA ; Eunseon GWAK ; Ju-Young SHIN ; Nam-Kyong CHOI ; Young June CHOE ; Seung-Ah CHOE
Journal of Korean Medical Science 2025;40(17):e63-
Background:
This study aimed to estimate the association between mRNA coronavirus disease 2019 (COVID-19) vaccine exposure during pregnancy and the risks of preterm birth and congenital malformations leveraging a national population data.
Methods:
This retrospective cohort study utilized national data from the National Health Insurance System, linking maternal and infant records with COVID-19 vaccination registries.Newborns with congenital malformations were identified using diagnosis codes. The analysis included women aged 20–49 who gave live births between February 2022 and December 2022. Odds ratios (ORs) for preterm birth and any congenital malformation per COVID-19 vaccination during pregnancy compared to 1:4 matched unvaccinated controls, adjusted for maternal age, residential area, employment, income, disability, month of conception, prepregnancy obesity, smoking, and severe acute respiratory syndrome coronavirus 2 infection prior to pregnancy, were calculated. We compared the risk of two outcomes between BNT162b2 and mRNA-1273.
Results:
Among 106,692 women who gave birth during the study period, 8,966 (8.4%) received a COVID-19 vaccination during pregnancy. Of the newborns, 7,039 (6.6%) were preterm births and 7,658 (7.2%) had congenital malformations. COVID-19 vaccination during pregnancy was associated with a comparable risk of preterm birth (OR, 1.03; 95% confidence interval [CI], 0.77–1.36) and a similar risk of congenital malformations (0.90; 95% CI, 0.72–1.12) compared to non-vaccinees. The ORs of preterm birth (1.02; 95% CI, 0.77–1.36) and congenital malformation (0.91; 95% CI, 0.73–1.14) for mRNA-1273 were comparable to those for BNT162b2.
Conclusion
COVID-19 vaccines during pregnancy poses no increased risk of preterm birth and congenital malformations compared to those not exposed to the vaccine, with similar risk levels observed between the two mRNA vaccines. This finding provides additional evidence supporting the safety of COVID-19 vaccines.
3.Radiation-Induced Cavernous Malformation in the Cerebellum:Clinical Features of Two Cases
Hyoung Soo CHOI ; Chae-Yong KIM ; Byung Se CHOI ; Seung Hyuck JEON ; In Ah KIM ; Joo-Young KIM ; Kyu Sang LEE ; Gheeyoung CHOE
Brain Tumor Research and Treatment 2025;13(2):58-64
Radiation-induced cavernous malformations (RICMs) are rare but significant late complications of highdose radiation therapy, particularly in young survivors of brain tumors. This report presents two cases of RICMs following aggressive multimodal treatment, including surgery, chemotherapy, and radiation therapy. Case 1 was a 22-year-old male patient with medulloblastoma treated with craniospinal irradiation, tumor bed boost, and tandem autologous peripheral blood stem cell transplantation. Approximately 8 years after treatment completion, routine follow-up imaging revealed a small focal hemorrhage in the right cerebellum, consistent with an RICM. The lesion was asymptomatic and managed conservatively with regular imaging, showing spontaneous resolution over time, with a significant size reduction noted 9 years post-treatment. Case 2 describes a 32-year-old male with an intracranial germinoma treated with whole-ventricular irradiation. Three years after treatment, the patient developed a symptomatic hemorrhagic RICM near a pre-existing developmental venous anomaly. Surgical resection and Gamma Knife Surgery stabilized the lesion; however, residual symptoms, including tremors and gait disturbances, persisted, affecting the patient’s daily activities. These cases illustrate the diverse clinical courses of RICMs, ranging from spontaneous resolution to the necessity of surgical intervention, and emphasize the importance of long-term surveillance and tailored management strategies for late-onset complications.
4.Radiation-Induced Cavernous Malformation in the Cerebellum:Clinical Features of Two Cases
Hyoung Soo CHOI ; Chae-Yong KIM ; Byung Se CHOI ; Seung Hyuck JEON ; In Ah KIM ; Joo-Young KIM ; Kyu Sang LEE ; Gheeyoung CHOE
Brain Tumor Research and Treatment 2025;13(2):58-64
Radiation-induced cavernous malformations (RICMs) are rare but significant late complications of highdose radiation therapy, particularly in young survivors of brain tumors. This report presents two cases of RICMs following aggressive multimodal treatment, including surgery, chemotherapy, and radiation therapy. Case 1 was a 22-year-old male patient with medulloblastoma treated with craniospinal irradiation, tumor bed boost, and tandem autologous peripheral blood stem cell transplantation. Approximately 8 years after treatment completion, routine follow-up imaging revealed a small focal hemorrhage in the right cerebellum, consistent with an RICM. The lesion was asymptomatic and managed conservatively with regular imaging, showing spontaneous resolution over time, with a significant size reduction noted 9 years post-treatment. Case 2 describes a 32-year-old male with an intracranial germinoma treated with whole-ventricular irradiation. Three years after treatment, the patient developed a symptomatic hemorrhagic RICM near a pre-existing developmental venous anomaly. Surgical resection and Gamma Knife Surgery stabilized the lesion; however, residual symptoms, including tremors and gait disturbances, persisted, affecting the patient’s daily activities. These cases illustrate the diverse clinical courses of RICMs, ranging from spontaneous resolution to the necessity of surgical intervention, and emphasize the importance of long-term surveillance and tailored management strategies for late-onset complications.
5.Maternal Exposures to COVID-19 Vaccine and Adverse Birth Outcomes:National Population Study in Korea
Kyuwon KIM ; Erdenetuya BOLORMAA ; Eunseon GWAK ; Ju-Young SHIN ; Nam-Kyong CHOI ; Young June CHOE ; Seung-Ah CHOE
Journal of Korean Medical Science 2025;40(17):e63-
Background:
This study aimed to estimate the association between mRNA coronavirus disease 2019 (COVID-19) vaccine exposure during pregnancy and the risks of preterm birth and congenital malformations leveraging a national population data.
Methods:
This retrospective cohort study utilized national data from the National Health Insurance System, linking maternal and infant records with COVID-19 vaccination registries.Newborns with congenital malformations were identified using diagnosis codes. The analysis included women aged 20–49 who gave live births between February 2022 and December 2022. Odds ratios (ORs) for preterm birth and any congenital malformation per COVID-19 vaccination during pregnancy compared to 1:4 matched unvaccinated controls, adjusted for maternal age, residential area, employment, income, disability, month of conception, prepregnancy obesity, smoking, and severe acute respiratory syndrome coronavirus 2 infection prior to pregnancy, were calculated. We compared the risk of two outcomes between BNT162b2 and mRNA-1273.
Results:
Among 106,692 women who gave birth during the study period, 8,966 (8.4%) received a COVID-19 vaccination during pregnancy. Of the newborns, 7,039 (6.6%) were preterm births and 7,658 (7.2%) had congenital malformations. COVID-19 vaccination during pregnancy was associated with a comparable risk of preterm birth (OR, 1.03; 95% confidence interval [CI], 0.77–1.36) and a similar risk of congenital malformations (0.90; 95% CI, 0.72–1.12) compared to non-vaccinees. The ORs of preterm birth (1.02; 95% CI, 0.77–1.36) and congenital malformation (0.91; 95% CI, 0.73–1.14) for mRNA-1273 were comparable to those for BNT162b2.
Conclusion
COVID-19 vaccines during pregnancy poses no increased risk of preterm birth and congenital malformations compared to those not exposed to the vaccine, with similar risk levels observed between the two mRNA vaccines. This finding provides additional evidence supporting the safety of COVID-19 vaccines.
6.Radiation-Induced Cavernous Malformation in the Cerebellum:Clinical Features of Two Cases
Hyoung Soo CHOI ; Chae-Yong KIM ; Byung Se CHOI ; Seung Hyuck JEON ; In Ah KIM ; Joo-Young KIM ; Kyu Sang LEE ; Gheeyoung CHOE
Brain Tumor Research and Treatment 2025;13(2):58-64
Radiation-induced cavernous malformations (RICMs) are rare but significant late complications of highdose radiation therapy, particularly in young survivors of brain tumors. This report presents two cases of RICMs following aggressive multimodal treatment, including surgery, chemotherapy, and radiation therapy. Case 1 was a 22-year-old male patient with medulloblastoma treated with craniospinal irradiation, tumor bed boost, and tandem autologous peripheral blood stem cell transplantation. Approximately 8 years after treatment completion, routine follow-up imaging revealed a small focal hemorrhage in the right cerebellum, consistent with an RICM. The lesion was asymptomatic and managed conservatively with regular imaging, showing spontaneous resolution over time, with a significant size reduction noted 9 years post-treatment. Case 2 describes a 32-year-old male with an intracranial germinoma treated with whole-ventricular irradiation. Three years after treatment, the patient developed a symptomatic hemorrhagic RICM near a pre-existing developmental venous anomaly. Surgical resection and Gamma Knife Surgery stabilized the lesion; however, residual symptoms, including tremors and gait disturbances, persisted, affecting the patient’s daily activities. These cases illustrate the diverse clinical courses of RICMs, ranging from spontaneous resolution to the necessity of surgical intervention, and emphasize the importance of long-term surveillance and tailored management strategies for late-onset complications.
7.Maternal Exposures to COVID-19 Vaccine and Adverse Birth Outcomes:National Population Study in Korea
Kyuwon KIM ; Erdenetuya BOLORMAA ; Eunseon GWAK ; Ju-Young SHIN ; Nam-Kyong CHOI ; Young June CHOE ; Seung-Ah CHOE
Journal of Korean Medical Science 2025;40(17):e63-
Background:
This study aimed to estimate the association between mRNA coronavirus disease 2019 (COVID-19) vaccine exposure during pregnancy and the risks of preterm birth and congenital malformations leveraging a national population data.
Methods:
This retrospective cohort study utilized national data from the National Health Insurance System, linking maternal and infant records with COVID-19 vaccination registries.Newborns with congenital malformations were identified using diagnosis codes. The analysis included women aged 20–49 who gave live births between February 2022 and December 2022. Odds ratios (ORs) for preterm birth and any congenital malformation per COVID-19 vaccination during pregnancy compared to 1:4 matched unvaccinated controls, adjusted for maternal age, residential area, employment, income, disability, month of conception, prepregnancy obesity, smoking, and severe acute respiratory syndrome coronavirus 2 infection prior to pregnancy, were calculated. We compared the risk of two outcomes between BNT162b2 and mRNA-1273.
Results:
Among 106,692 women who gave birth during the study period, 8,966 (8.4%) received a COVID-19 vaccination during pregnancy. Of the newborns, 7,039 (6.6%) were preterm births and 7,658 (7.2%) had congenital malformations. COVID-19 vaccination during pregnancy was associated with a comparable risk of preterm birth (OR, 1.03; 95% confidence interval [CI], 0.77–1.36) and a similar risk of congenital malformations (0.90; 95% CI, 0.72–1.12) compared to non-vaccinees. The ORs of preterm birth (1.02; 95% CI, 0.77–1.36) and congenital malformation (0.91; 95% CI, 0.73–1.14) for mRNA-1273 were comparable to those for BNT162b2.
Conclusion
COVID-19 vaccines during pregnancy poses no increased risk of preterm birth and congenital malformations compared to those not exposed to the vaccine, with similar risk levels observed between the two mRNA vaccines. This finding provides additional evidence supporting the safety of COVID-19 vaccines.
8.Methodology of comparative studies on the relative effectiveness of COVID-19 vaccines: a systematic review
Erdenetuya BOLORMAA ; Jiae SHIM ; Young-Sook CHOI ; Donghyok KWON ; Young June CHOE ; Seung-Ah CHOE
Osong Public Health and Research Perspectives 2024;15(5):395-408
Objectives:
This study aimed to comprehensively outline the methodological approaches used in published research comparing the vaccine effectiveness (VE) of coronavirus disease 2019 (COVID-19) vaccines.
Methods:
A systematic search was conducted on June 13, 2024, to identify comparative studies evaluating the effectiveness of mRNA versus non-mRNA and monovalent versus bivalent COVID-19 vaccines. We screened titles, abstracts, and full texts, collecting data on publication year, country, sample size, study population composition, study design, VE estimates, outcomes, and covariates. Studies that reported relative VE (rVE) were analyzed separately from those that did not.
Results:
We identified 25 articles comparing rVE between mRNA and non-mRNA COVID-19 vaccines, as well as between monovalent and bivalent formulations. Among the studies assessing VE by vaccine type, 126 did not provide rVE estimates. Comparative VE studies frequently employed retrospective cohort designs. Among the definitions of rVE used, the most common were hazard ratio and absolute VE, calculated as (1−odds ratio)×100. Studies were most frequently conducted in the United Kingdom and the United States, and the most common outcome was infection. Most targeted the general population and assessed the VE of mRNA vaccines using the AstraZeneca vaccine as a reference. A small proportion, 7.3% (n=11), did not adjust for any variables. Only 3 studies (2.0%) adjusted for all core confounding variables recommended by the World Health Organization.
Conclusion
Few comparative studies of COVID-19 vaccines have incorporated rVE methodologies. Reporting rVE and employing a consistent set of covariates can broaden our understanding of COVID-19 vaccines.
9.Methodology of comparative studies on the relative effectiveness of COVID-19 vaccines: a systematic review
Erdenetuya BOLORMAA ; Jiae SHIM ; Young-Sook CHOI ; Donghyok KWON ; Young June CHOE ; Seung-Ah CHOE
Osong Public Health and Research Perspectives 2024;15(5):395-408
Objectives:
This study aimed to comprehensively outline the methodological approaches used in published research comparing the vaccine effectiveness (VE) of coronavirus disease 2019 (COVID-19) vaccines.
Methods:
A systematic search was conducted on June 13, 2024, to identify comparative studies evaluating the effectiveness of mRNA versus non-mRNA and monovalent versus bivalent COVID-19 vaccines. We screened titles, abstracts, and full texts, collecting data on publication year, country, sample size, study population composition, study design, VE estimates, outcomes, and covariates. Studies that reported relative VE (rVE) were analyzed separately from those that did not.
Results:
We identified 25 articles comparing rVE between mRNA and non-mRNA COVID-19 vaccines, as well as between monovalent and bivalent formulations. Among the studies assessing VE by vaccine type, 126 did not provide rVE estimates. Comparative VE studies frequently employed retrospective cohort designs. Among the definitions of rVE used, the most common were hazard ratio and absolute VE, calculated as (1−odds ratio)×100. Studies were most frequently conducted in the United Kingdom and the United States, and the most common outcome was infection. Most targeted the general population and assessed the VE of mRNA vaccines using the AstraZeneca vaccine as a reference. A small proportion, 7.3% (n=11), did not adjust for any variables. Only 3 studies (2.0%) adjusted for all core confounding variables recommended by the World Health Organization.
Conclusion
Few comparative studies of COVID-19 vaccines have incorporated rVE methodologies. Reporting rVE and employing a consistent set of covariates can broaden our understanding of COVID-19 vaccines.
10.Adverse Events Following COVID-19Vaccination in Adolescents: Insights From Pharmacovigilance Study of VigiBase
Dong Hyuk KIM ; Ju Hwan KIM ; In-Sun OH ; Young June CHOE ; Seung-Ah CHOE ; Ju-Young SHIN
Journal of Korean Medical Science 2024;39(8):e76-
Background:
During coronavirus disease 2019 (COVID-19) pandemic, several COVID-19 vaccines were licensed with fast-track procedures. Although these vaccines have demonstrated high immunogenicity, there has been concerns on the serious adverse events (AEs) following COVID-19 vaccination among adolescents. We aimed to analyze comparative safety of COVID-19 vaccination in adolescents.
Methods:
In this pharmacovigilance study, we performed a disproportionality analysis using VigiBase, the World Health Organization’s global individual case safety report (ICSR) database. To compare serious AEs reported following COVID-19 vaccines vs. all other vaccines in adolescents aged 12–17 years, ICSRs following any vaccines on adolescents aged 12–17 years were included, defining cases as reports with the AEs of interest, with all other AEs as non-cases. The AEs of interest were myocarditis/pericarditis, multisystem inflammatory syndrome/Kawasaki disease (MIS/KD), anaphylaxis, Guillain-Barré syndrome (GBS), and immune thrombocytopenia (ITP). We conducted a disproportionality analysis to estimate reporting odds ratio (ROR) with 95% confidence interval (CI) for each AE of interest, adjusted for sex by using logistic regression.
Results:
Of 99,735 AE reports after vaccination in adolescents, 80,018 reports were from COVID-19 vaccinated adolescents (52.9% females; 56.3% America). The AEs of interest were predominantly reported as serious AE (76.1%) with mRNA vaccines (99.4%). Generally, higher reporting odds for the AEs were identified following COVID-19 vaccination in adolescents;myocarditis/pericarditis (2,829 reports for the COVID-19 vaccine vs. 35 for all other vaccines, adjusted ROR [aROR], 19.61; 95% CI, 14.05–27.39), and MIS/KD (104 vs. 6, aROR, 4.33; 95% CI, 1.89–9.88). The reporting odds for anaphylaxis (515 vs. 165, aROR, 0.86; 95% CI, 0.72– 1.02), GBS (94 vs. 40, aROR, 0.64; 95% CI, 0.44–0.92) and ITP (52 vs. 12, aROR, 1.12; 95% CI, 0.59–2.09) were not significantly higher following COVID-19 vaccination.
Conclusion
In this study, there were disproportionate reporting of immune-related AEs following COVID-19 vaccination. While awaiting definitive evidence, there is a need to closely monitor for any signs of immune-related AEs following COVID-19 vaccination among adolescents.

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