Epidemiology and Health

COVID-19: Original Article

Comorbidity network of post-traumatic stress and depressive symptoms during the COVID-19 pandemic in Korea: Yujin Lee, Ji Su Yang, Alexander C. Tsai, Jee In Kang, Hearan Koo, Hyeon Woo Yim, Hyeon Chang Kim, Sun Jae Jung; Epidemiol Health. 2026;48:e2026006. Published online January 23, 2026; DOI: https://doi.org/10.4178/epih.e2026006

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Abstract Summary PDF Supplementary Material: Abstract
OBJECTIVES
The coronavirus disease 2019 (COVID-19) pandemic had direct effects on population health through infection and morbidity, as well as indirect effects on population mental health. We estimated the network structure of post-traumatic stress symptoms (PTSS) and depressive symptoms throughout the pandemic in Korea and aimed to identify the most central and bridging symptoms.
METHODS
Participants aged 30–64 years completed mental health surveys across 3 phases of the COVID-19 pandemic: March 2020 (n=1,925), February–March 2021 (n=1,754), and December 2021–January 2022 (n=1,595). Using PTSS and depressive symptom data, we conducted network analyses, and the primary measures of symptom importance (centrality) were expected influence and bridge expected influence.
RESULTS
In the comorbidity network, although the most central symptoms fluctuated over the course of the pandemic, sleep problems were consistently identified as the most influential bridge symptoms throughout. The symptom network structure differed between the subacute and chronic phases of the pandemic.
CONCLUSIONS
We found evidence of changes in the network structure of PTSS and depressive symptoms, even as sleep problems retained a consistent role as a bridging symptom. Although overall network structures varied across phases of the pandemic, the bridging role of sleep-related symptoms remained consistently strong, suggesting that sleep problems may represent a general and enduring mechanism underlying PTSS–depression comorbidity. During future pandemics, prompt screening for sleep problems may help prevent the development of comorbidity between PTSS and depressive symptoms.; Summary

Korean summary
- 팬데믹 아급성기에서 만성기로 진행되며 외상후 스트레스 증상 및 우울증상의 네트워크 구조에서 중심증상 변화가 관측되었다. - 아급성기에는 ‘침습적 재경험(flashbacks)’과 ‘우울한 기분(depressed mood)’, 만성기에는 ‘우울한기분(depressed mood)’과 ‘무모하거나 자기파괴적인 행동(reckless behavior)’이 중심증상이었다. - ‘수면 문제(sleeping problems)’는 전 기간 동안 핵심 브리지증상으로 나타났다.

Key Message
- The comorbidity network between PTSS and depressive symptoms shifted from the subacute to the chronic phase of the COVID-19 pandemic, with changes in central symptoms. - “Flashbacks” and “depressed mood” were central in the subacute phase, whereas “depressed mood” and “reckless behavior” were central in the chronic phase. - “Sleep problems” consistently acted as a key bridge symptom, suggesting its potential as an intervention target.

COVID-19: Cohort Profile

Cohort profile: Cardiovascular Metabolic Etiological Research Center COVID-19 Mental Health Survey (CC-MHS): Sun Jae Jung, Dongkyu Lee, Ji Su Yang, Sunghyuk Kang, Hyejin Kim, Jeong Hyun Ahn, Yunseong Heo, Jieun Noh, Changhyun Kim, Hyeon Chang Kim; Epidemiol Health. 2025;47:e2025033. Published online June 30, 2025; DOI: https://doi.org/10.4178/epih.e2025033

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Abstract Summary PDF: Abstract
The Cardiovascular Metabolic Etiological Research Center COVID-19 Mental Health Survey (CC-MHS) is a comprehensive longitudinal cohort study investigating the mental health impact of the coronavirus disease 2019 pandemic by utilizing pre-existing baseline data from the Cardiovascular Metabolic Etiological Research Center cohort (2013-2018). This study assesses physical health, lifestyle changes, and mental health using validated tools, including the Patient Health Questionnaire-9, Generalized Anxiety Disorder-7, and the PTSD Checklist for DSM-5, and evaluates a population of urban and suburban Korean participants across multiple dimensions. Through online surveys, the research identified gender-specific social support mechanisms, showing that men benefit from larger social networks, whereas women derive protective effects from stronger emotional connections. Key findings underscore complex interactions among demographic factors, psychological variables, and public health responses, especially in the context of vaccination attitudes and trust in pandemic management. The CC-MHS delivers critical insights into mental health trajectories during global health crises, offering valuable evidence for developing adaptive public health strategies and for understanding the intricate relationships between individual psychological resilience and broader societal health challenges.; Summary

Korean summary
본 CC-MHS 코호트는 팬데믹 이전 4,060명 대상 CMERC 기초자료 활용하였다 본 CC-MHS 코호트는 우울, 불안, PTSD 등 정신건강 평가를 7차례 추적조사하였다. 본 코호트에서는 성별 보호요인과 사회적 지지·신뢰의 중요성 규명하였다.

Key Message
In CC-MHS, we utilized pre-pandemic baseline data from 4,060 adults in the CMERC cohort. We conducted 7 waves of mental health surveys assessing depression, anxiety, PTSD, and resilience. In this cohort, we identified gender-specific protective factors and emphasized the importance of social support and trust.

COVID-19: Original Article

Physical and mental health characteristics related to trust in and intention to receive COVID-19 vaccination: results from a Korean community-based longitudinal study: Ye Jin Jeon, Youngrong Lee, Ji Su Yang, Young Su Park, Sun Jae Jung; Epidemiol Health. 2022;44:e2022064. Published online August 3, 2022; DOI: https://doi.org/10.4178/epih.e2022064

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2 Web of Science
2 Crossref

Abstract Summary PDF Supplementary Material

Abstract

OBJECTIVES
The aim of this study was to explore factors affecting attitudes toward coronavirus disease 2019 (COVID-19) vaccination, including socio-demographic characteristics and mental health status during the pandemic.

METHODS

This study analyzed responses from 1,768 participants who were originally included in a community cohort study and responded to 3 online surveys related to COVID-19 (March 2020 to March 2021). The k-means method was used to cluster trust in and intention to receive COVID-19 vaccination. Baseline (2013-2018) socio-demographic characteristics, physical health status, and depressive symptoms were analyzed as exposure variables, and current mental health status was included in the analyses.

RESULTS

Almost half of all participants were classified into the moderate trust and high intention cluster (n=838, 47.4%); those with high trust and high intention accounted only for 16.9%. They tended to be older, had high-income levels, and engaged in regular physical activity at baseline (p<0.05), and their sleep quality and psychological resilience were relatively high compared to other groups.

CONCLUSIONS

Our results suggest that more efforts are required to enhance the perceived need for and trust in COVID-19 vaccination.

Summary

Korean summary
•본 연구는 코로나19 관련 온라인, 모바일 설문조사에 응답한 1,768명을 대상으로 코로나19 유행 동안의 정신건강 상태와 백신 접종에 대한 태도 (백신에 대한 믿음, 백신에 대한 접종 의사) 사이의 관련성을 파악하고자 하였다. •연구결과 우울, 불안, 외로움, 회복탄력성 등과 같은 정신건강 상태가 나쁜 사람은 백신에 대한 접종 의사가 높을 오즈가 그렇지 않은 사람에 비해 높았으며, 이는 통계적으로 유의하였다.

Key Message
In this community-based study including 1,768 participants who responded online survey related to COVID-19, we investigate the relationship between mental health during the pandemic and attitude toward COVID-19 vaccine (trust and intention). Each of the mental symptoms, including depression, anxiety, and loneliness, was significantly associated with higher intention to COVID-19 vaccine. Our results suggest that more efforts are required to enhance the perceived need for and trust in COVID-19 vaccination.

Citations

Citations to this article as recorded by

Changing dynamics of tuberculosis incidence in Northwest Iran (East Azerbaijan): 15-Year joinpoint time trend analysis
Lotfali Haghiri, Fatemeh Rostampour, Mohammad Heidari
BMC Pulmonary Medicine.2026;[Epub] CrossRef
Cohort profile: Cardiovascular Metabolic Etiological Research Center COVID-19 Mental Health Survey (CC-MHS)
Sun Jae Jung, Dongkyu Lee, Ji Su Yang, Sunghyuk Kang, Hyejin Kim, Jeong Hyun Ahn, Yunseong Heo, Jieun Noh, Changhyun Kim, Hyeon Chang Kim
Epidemiology and Health.2025; 47: e2025033. CrossRef

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