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3 "Yunha Noh"
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Original Articles
Evaluation of gestational age by pregnancy outcomes and distribution of pregnancy-related codes in Korean claims data
Woo-Jung Kim, Yunha Noh, Yongtai Cho, Eun-Young Choi, HyunJoo Lim, Hyesung Lee, Ju-Young Shin
Epidemiol Health. 2026;48:e2026007.   Published online February 4, 2026
DOI: https://doi.org/10.4178/epih.e2026007
  • 3,178 View
  • 100 Download
AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
This study aimed to evaluate a fixed-duration algorithm for gestational age (GA) estimation according to pregnancy outcomes and to describe the GA distribution of pregnancy-related codes in Korea.
METHODS
We included 351,055 pregnancy episodes (2019–2022) from linked data between the National Health Insurance Service and the Korea Immunization Registry Information System (KIRIS). GA from claims data was estimated by subtracting fixed durations from the delivery date (algorithm-based GA), and GA derived from KIRIS was defined as the gold standard. Accuracy was evaluated as the proportion of episodes in which the difference between the estimated GA and the reference standard fell within ±2 weeks. We described the distributions of the GA at which each prenatal test, pregnancy complication, and diagnostic code was recorded.
RESULTS
Algorithm-based GA estimation showed high accuracy for live births (92.2% within ±2 weeks) but markedly lower accuracy for non-live birth outcomes, including stillbirth (3.3%), termination (7.2%), spontaneous abortion (45.2%), and ectopic pregnancy (20.0%). In additional analyses aimed at identifying potential indicators for improving GA estimation, most events occurred within clinically expected timeframes, although some individual codes exhibited poor temporal alignment.
CONCLUSIONS
Algorithm-based GA estimation using claims data performed well for live births but demonstrated limited accuracy for non-live birth outcomes. Incorporating information from prenatal tests and pregnancy complications may enhance GA estimation.
Summary
Korean summary
본 연구는 국내 전국민 단위 청구자료와 예방접종 등록자료를 연계하여 고정 임신기간 기반 알고리즘의 재태연령 추정 정확도를 임신 결과별로 체계적으로 검증하였다. 출생아에서는 ±2주 기준 92.2%의 높은 정확도를 보였으나, 사산·인공임신중절·자연유산·자궁외임신 등 비출생 결과에서는 현저히 낮은 정확도를 보여 결과 유형에 따른 성능 이질성이 확인되었다. 산전검사 및 임신 합병증과 같은 시간 민감적 임상지표를 통합한 계층적 접근이 청구자료 기반 재태연령 추정의 타당도 향상에 기여할 수 있다.
Key Message
Using nationwide linked claims and immunization registry data in Korea, this study systematically validated the performance of a fixed-duration algorithm for gestational age estimation across pregnancy outcomes. While high accuracy was observed for live births (92.2% within ±2 weeks), substantially poorer performance was identified for non–live-birth outcomes, indicating marked outcome-specific heterogeneity. Integration of time-sensitive clinical indicators, including prenatal tests and pregnancy complications, may enhance the validity of gestational age estimation in administrative data research.
Barriers to COVID-19 vaccine surveillance: the issue of under-reporting adverse events
Yunha Noh, Hwa Yeon Ko, Ju Hwan Kim, Dongwon Yoon, Young June Choe, Seung-Ah Choe, Jaehun Jung, Ju-Young Shin
Epidemiol Health. 2023;45:e2023054.   Published online June 7, 2023
DOI: https://doi.org/10.4178/epih.e2023054
  • 23,058 View
  • 169 Download
  • 10 Web of Science
  • 11 Crossref
AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
This study investigated the reporting rates of adverse events following immunization (AEFIs) to the spontaneous reporting system (SRS) and its predictors among individuals with AEFIs after coronavirus disease 2019 (COVID-19) vaccination.
METHODS
A cross-sectional, web-based survey was conducted from December 2, 2021 to December 20, 2021, recruiting participants >14 days after completion of a primary COVID-19 vaccination series. Reporting rates were calculated by dividing the number of participants who reported AEFIs to the SRS by the total number of participants who experienced AEFIs. We estimated adjusted odds ratios (aORs) using multivariate logistic regression to determine factors associated with spontaneous AEFIs reporting.
RESULTS
Among 2,993 participants, 90.9% and 88.7% experienced AEFIs after the first and second vaccine doses, respectively (reporting rates, 11.6 and 12.7%). Furthermore, 3.3% and 4.2% suffered moderate to severe AEFIs, respectively (reporting rates, 50.5 and 50.0%). Spontaneous reporting was more prevalent in female (aOR, 1.54; 95% confidence interval [CI], 1.31 to 1.81); those with moderate to severe AEFIs (aOR, 5.47; 95% CI, 4.45 to 6.73), comorbidities (aOR, 1.31; 95% CI, 1.09 to 1.57), a history of severe allergic reactions (aOR, 2.02; 95% CI, 1.47 to 2.77); and those who had received mRNA-1273 (aOR, 1.25; 95% CI, 1.05 to 1.49) or ChAdOx1 (aOR, 1.62; 95% CI, 1.15 to 2.30) vaccines versus BNT162b2. Reporting was less likely in older individuals (aOR, 0.98; 95% CI, 0.98 to 0.99 per 1-year age increment).
CONCLUSIONS
Spontaneous reporting of AEFIs after COVID-19 vaccination was associated with younger age, female sex, moderate to severe AEFIs, comorbidities, history of allergic reactions, and vaccine type. AEFIs under-reporting should be considered when delivering information to the community and in public health decision-making.
Summary
Korean summary
본 연구는 국내 19-49세 성인을 대상으로, 코로나19 예방 백신 접종 후 이상반응 경험에 대한 자발적 보고율을 조사하고, 자발적 보고와 관련된 요인을 파악하고자 하였다. 2021년 12월 2일부터 20일까지 온라인 설문조사를 통하여 자료를 수집하였으며, 연구대상자는 코로나19 예방 백신의 기초접종을 완료한 후 2주 경과한 19-49세 성인으로, 전국 대표성을 확보하기 위해 성별, 연령, 지역별로 층화하여 모집하였다. 이상반응 자발적 보고율은 1차 접종과 2차 접종 후 각각 약 11.6%, 12.7%로 나타났으며, 중등도에서 중증의 이상반응에 대한 자발적 보고율은 약 50.5%, 50.0%로 나타났다. 이상반응 자발적 보고율 관련 영향요인으로는 젊은 연령층, 여성, 이상반응의 중증도, 동반질환, 알러지 반응 이력, 기초접종 백신 종류가 포함되었다.
Key Message
Spontaneous reporting rates of adverse events following immunization (AEFIs) against coronavirus disease 2019 (COVID-19) were low, at around 12 % of any AEFIs and 50 % of moderate-to-severe AEFIs. Younger age, female sex, severe AEFIs, comorbidities, history of allergic reactions, and the type of COVID-19 vaccine were associated with the AEFIs reporting.

Citations

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  • Post-marketing Safety Surveillance of 23-Valent Pneumococcal Polysaccharide Vaccine Administered Alone and Concomitantly with Influenza Vaccine in Individuals Aged 2 Years and Older in China
    Yun-feng Shi, Lin-hang Ju, Kang-ning Wang, Yu Pan, Yu-ying Zou, Xi Lu, Ling Tuo, Wen-tao Zou, Ming-wei Wei, Yan-wei Zhao, Hong-xing Pan
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    Kotonari AOKI, Yosuke NISHIDA, Suguru NOZUE
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    Wojciech Nazar, Jan Romantowski, Marek Niedoszytko, Ludmiła Daniłowicz-Szymanowicz
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Predictors of COVID-19 booster vaccine hesitancy among fully vaccinated adults in Korea: a nationwide cross-sectional survey
Yunha Noh, Ju Hwan Kim, Dongwon Yoon, Young June Choe, Seung-Ah Choe, Jaehun Jung, Sang-Won Lee, Ju-Young Shin
Epidemiol Health. 2022;44:e2022061.   Published online July 22, 2022
DOI: https://doi.org/10.4178/epih.e2022061
  • 24,124 View
  • 387 Download
  • 21 Web of Science
  • 19 Crossref
AbstractAbstract AbstractSummary PDFSupplementary Material
Abstract
OBJECTIVES
This study explored predictors of coronavirus disease 2019 (COVID-19) booster hesitancy among fully vaccinated young adults and parental COVID-19 vaccine hesitancy for their children.
METHODS
This cross-sectional study administered an online survey from December 2 to December 20, 2021. We enrolled participants aged 18-49 years, for whom ≥2 weeks had passed after their initial COVID-19 vaccination. We estimated odds ratios (ORs) with 95% confidence intervals (CIs) using multivariate logistic regression to evaluate factors associated with booster/vaccine hesitancy.
RESULTS
Among the 2,993 participants, 48.8% showed hesitancy (wait and see: 40.2%; definitely not: 8.7%). Booster hesitancy was more common among women (OR, 1.25; 95% CI, 1.05 to 1.50), younger people (OR, 1.44; 95% CI, 1.17 to 1.77), those with a lower education level (OR, 2.05; 95% CI, 1.10 to 3.82), those who received the mRNA-1273 vaccine type (OR, 2.01; 95% CI, 1.65 to 2.45), and those who experienced serious adverse events following previous COVID-19 vaccination (OR, 2.03; 95% CI, 1.47 to 2.80). The main reasons for booster hesitancy were concerns about safety (54.1%) and doubts about efficacy (29.8%). Among the 1,020 respondents with children aged <18 years, 65.8% were hesitant to vaccinate their children against COVID-19; hesitancy was associated with younger parental age, education level, the type of vaccine the parent received, and a history of COVID-19 infection.
CONCLUSIONS
Concerns about the efficacy and safety of COVID-19 vaccines were the major barrier to booster acceptance. The initial COVID-19 vaccine type (mRNA-1273), young age, gender (women), a low education level, and adverse events after the first COVID-19 vaccine were key predictors of booster hesitancy.
Summary
Korean summary
본 연구는 국내 19-49세 성인을 대상으로, 코로나19 3차접종 의향과 그들의 18세 미만 자녀에 대한 코로나19 기초접종 의향을 조사하고, 코로나19 백신접종 기피와 관련된 요인을 파악하고자 하였다. 2021년 12월 2일부터 20일까지 온라인 설문조사를 통하여 자료를 수집하였으며, 연구대상자는 코로나19 기초접종을 완료한 후 2주 경과한 19-49세 성인으로, 전국 대표성을 확보하기 위해 성별, 연령, 지역별로 층화하여 모집하였다. 코로나19 3차접종 기피율은 약 48.8%로 나타났으며, 접종 기피 관련 영향요인으로는 젊은 연령층, 여성, 낮은 교육수준, 기초접종 백신 종류, 기초접종 후 중증 이상반응 경험이 포함되었으며, 18세 미만 자녀에 대한 코로나19 기초접종 기피율은 65.8%로, 관련 영향요인으로는 젊은 부모 연령, 교육수준, 부모의 기초접종 백신 종류, 코로나19 감염 과거력이 포함되었다.
Key Message
Concerns about the safety and efficacy of COVID-19 vaccines were the major barrier to booster acceptance; the initial COVID-19 vaccine type (mRNA-1273), younger age, gender (women), a low education level, and adverse events after the first COVID-19 vaccine were key predictors of booster hesitancy.

Citations

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