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Original Article
Impact of long COVID-19 on posttraumatic stress disorder as modified by health literacy: an observational study in Vietnam
Han Thi Vo, Tien Duc Dao, Tuyen Van Duong, Tan Thanh Nguyen, Binh Nhu Do, Tinh Xuan Do, Khue Minh Pham, Vinh Hai Vu, Linh Van Pham, Lien Thi Hong Nguyen, Lan Thi Huong Le, Hoang Cong Nguyen, Nga Hoang Dang, Trung Huu Nguyen, Anh The Nguyen, Hoan Van Nguyen, Phuoc Ba Nguyen, Hoai Thi Thanh Nguyen, Thu Thi Minh Pham, Thuy Thi Le, Thao Thi Phuong Nguyen, Cuong Quoc Tran, Kien Trung Nguyen
Osong Public Health Res Perspect. 2024;15(1):33-44.   Published online February 19, 2024
DOI: https://doi.org/10.24171/j.phrp.2023.0261
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  • 8 Download
Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The prevalence of posttraumatic stress disorder (PTSD) has increased, particularly among individuals who have recovered from coronavirus disease 2019 (COVID-19) infection. Health literacy is considered a “social vaccine” that helps people respond effectively to the pandemic. We aimed to investigate the association between long COVID-19 and PTSD, and to examine the modifying role of health literacy in this association. Methods: A cross-sectional study was conducted at 18 hospitals and health centers in Vietnam from December 2021 to October 2022. We recruited 4,463 individuals who had recovered from COVID-19 infection for at least 4 weeks. Participants provided information about their sociodemographics, clinical parameters, health-related behaviors, health literacy (using the 12-item short-form health literacy scale), long COVID-19 symptoms and PTSD (Impact Event Scale-Revised score of 33 or higher). Logistic regression models were used to examine associations and interactions. Results: Out of the study sample, 55.9% had long COVID-19 symptoms, and 49.6% had PTSD. Individuals with long COVID-19 symptoms had a higher likelihood of PTSD (odds ratio [OR], 1.86; 95% confidence interval [CI], 1.63–2.12; p<0.001). Higher health literacy was associated with a lower likelihood of PTSD (OR, 0.98; 95% CI, 0.97–0.99; p=0.001). Compared to those without long COVID-19 symptoms and the lowest health literacy score, those with long COVID-19 symptoms and a 1-point health literacy increment had a 3% lower likelihood of PTSD (OR, 0.97; 95% CI, 0.96–0.99; p=0.001). Conclusion: Health literacy was found to be a protective factor against PTSD and modified the negative impact of long COVID-19 symptoms on PTSD.
Short Communication
Characteristics of a large outbreak arising from a school field trip after COVID-19 restrictions were eased in 2022
Sueng-Jin Kim, Eun-Young Kim, Jeonghee Yu
Osong Public Health Res Perspect. 2024;15(1):83-89.   Published online February 5, 2024
DOI: https://doi.org/10.24171/j.phrp.2023.0264
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study analyzed a large outbreak of coronavirus disease 2019 (COVID-19) that occurred during a high school field trip in the Jeonbuk region and aimed to identify risk factors for COVID-19 infection, with the goal of preventing such outbreaks in the future. Methods: A retrospective cohort study of 737 participants, including 668 students and 69 staff at High School A, was designed to describe the epidemiological characteristics of this large COVID-19 outbreak. Logistic regression analysis was performed to calculate relative risks (odds ratios [ORs]) and 95% confidence intervals (CIs). Results: There were 190 confirmed cases (174 students, 16 staff), with an attack rate of 25.8%. Small outbreaks were decreasing before the field trip, but this trend reversed after the trip, leading to larger outbreaks. Logistic regression showed an OR of 2.39 (95% CI, 1.66–3.43; p<0.05) for COVID-19 infection among field trip participants. Among them, 11th graders had an OR of 2.32 (95% CI, 1.53–3.52; p<0.05) compared to 10th graders, while no significant risk difference was found within same-grade teams. Conclusion: There was a high risk for COVID-19 transmission during extracurricular activities with a large number of participants, such as field trips, even after the nationwide Omicron variant epidemic subsided. Even when students are separated into teams and follow different routes, it is challenging to design routes that entirely prevent contact between teams. Thus, programs should be designed carefully, and students with symptoms should be identified before and during the program to isolate them promptly.
Original Articles
Characteristics and related factors of waterborne and foodborne infectious disease outbreaks before and after the onset of the COVID-19 pandemic (2017–2021) in the Republic of Korea: a descriptive study
Eunkyoung Kim, Bryan Inho Kim
Osong Public Health Res Perspect. 2023;14(6):483-493.   Published online December 14, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0221
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The incidence of waterborne and foodborne infectious diseases (WFIDs) continues to increase annually, attracting significant global attention. This study examined trends in WFID outbreaks in the Republic of Korea over the 5-year period before and during the coronavirus disease 2019 (COVID-19) pandemic and provided foundational data to establish measures for the prevention and control of WFID outbreaks. Methods: We analyzed 2,541 WFID outbreaks from 2017 to 2021 (42,805 cases) that were reported through the Integrated Disease Surveillance System of the Korea Disease Control and Prevention Agency. Outbreaks were defined as the occurrence of gastrointestinal symptoms in ≥2 individuals within a group with temporal and regional epidemiological associations. The related factors associated with WFID outbreaks during the observation period were statistically analyzed. Results: The total number of WFID outbreaks significantly decreased in 2020 during the COVID-19 pandemic and increased to the pre-pandemic level in 2021. Different patterns were observed for each pathogen. The incidence of Salmonella outbreaks more than doubled, while norovirus outbreaks decreased significantly. Conclusion: WFID outbreaks in the Republic of Korea showed different patterns before and during the COVID-19 pandemic, influenced by infection control measures and changes in dietary consumption patterns. Outbreaks of some diseases increased, but the infection control measures applied during the pandemic resulted in a significant decrease in the overall number of WFID outbreaks. This highlights the importance of strengthening the management strategies for outbreak prevention through hygiene inspections, long-term monitoring, education, and promotion by conducting multidimensional analyses to understand the complex related factors.
Factors affecting depression and health-related quality of life in the elderly during the COVID-19 pandemic
Deok-Ju Kim
Osong Public Health Res Perspect. 2023;14(6):520-529.   Published online November 16, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0166
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study investigated changes in the health behaviors of the elderly due to coronavirus disease 2019 (COVID-19), concerns due to COVID-19, depression, and healthrelated quality of life (HRQOL), and aimed to identify factors that affect depression and HRQOL in the elderly. Methods: This study was conducted using data from the 2021 Community Health Survey of the Korea Disease Control and Prevention Agency. From a total sample size of 229,242 individuals, 74,376 elderly people aged 65 or older were selected as subjects, and changes in health behaviors, concerns due to COVID-19, depression, and HRQOL were measured and analyzed. Results: The level of depression associated with sleep and fatigue was high. The lowest HRQOL was related to physical pain and discomfort, while the most common concerns were related to economic difficulties. Factors influencing depression included worries about infection and economic harm, while factors impacting HRQOL encompassed concerns about infection, economic harm, and criticism from others. Conclusion: If an infectious disease situation such as COVID-19 reoccurs in the future, it will be necessary to encourage participation in hybrid online and offline programs at senior welfare centers. This should also extend to community counseling institutions like mental health welfare centers. Additionally, establishing connections with stable senior job projects can help to mitigate the effects of social interaction restrictions, physical and psychological health issues, and economic difficulties experienced by the elderly.
Evaluation of COVID-19 vaccine effectiveness in different high-risk facility types during a period of Delta variant dominance in the Republic of Korea: a cross-sectional study
Min Jei Lee, Myung-Jae Hwang, Dong Seob Kim, Seon Kyeong Park, Jihyun Choi, Ji Joo Lee, Jong Mu Kim, Young-Man Kim, Young-Joon Park, Jin Gwack, Sang-Eun Lee
Osong Public Health Res Perspect. 2023;14(5):418-426.   Published online October 19, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0188
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
We evaluated the effectiveness of coronavirus disease 2019 vaccination in high-risk facilities in the Republic of Korea during the period when the highly transmissible Delta variant was prevalent. Additionally, we aimed to explore any disparities in vaccine effectiveness (VE) across various types of institutions, specifically distinguishing between non-medical and medical establishments. Methods: We examined 8 outbreak clusters covering 243 cases and 895 contacts from 8 high-risk facilities divided into 2 groups: group A (4 non-medical institutions) and group B (4 medical institutions). These clusters were observed from July 27, 2021 to October 16, 2021 for the attack rate (AR) and VE with respect to disease severity. A generalized linear model with a binomial distribution was used to determine the odds ratio (OR) for disease severity and death. Results: AR was notably lower in group B (medical institutions). Furthermore, VE analysis revealed that group A exhibited higher effectivity for disease severity and death than group B. The OR for disease severity was 0.24 (95% confidence interval [CI], 0.03–2.16) for group A and 0.27 (95% CI, 0.12–0.64) for group B, with the OR for death at 0.12 (95% CI, 0.01–1.32) in group A and 0.34 (95% CI, 0.14–0.87) in group B. Conclusion: Although VE may vary across institutions, our findings underscore the importance of implementing vaccinations in high-risk facilities. Customized vaccination programs, tailored response plans, and competent management personnel are essential for effectively addressing and mitigating public health challenges.
Estimating the prevalence of oral manifestations in COVID-19 patients: a systematic review
Ankita Gupta, Kriti Shrivastav, Amit Agrawal, Abhishek Purohit, Roshan Chanchlani
Osong Public Health Res Perspect. 2023;14(5):388-417.   Published online September 19, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0033
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
Patients with coronavirus disease 2019 (COVID-19) present with a variety of oral manifestations. Therefore, we conducted a systematic review to estimate the prevalence of oral lesions among COVID-19 patients. Methods: An extensive literature search of several electronic bibliographic databases (PubMed, Scopus, Science Direct, Litcovid) was conducted to retrieve all articles published in the English language from January 1, 2020 to March 31, 2023 that reported the prevalence of oral manifestations among COVID-19 patients. A meta-analysis of pooled prevalence was performed using Jamovi ver. 2.3 (2022). The I2 and Q statistics were used to assess heterogeneity between studies, and p-values <0.01 were considered statistically significant. Results: In total, 79 studies with data from 13,252 patients were included. The articles were predominantly published in 2020 (n=33), and Italy was the most common country (n=14). Most of the affected patients more than 50 years old and women (56.6%). The most common sites of involvement were the tongue (n=65), followed by the oral mucosa (n=37) and lips (n=19). High heterogeneity was found between studies. The most common oral manifestation was taste alteration, followed by xerostomia and ulceration, showing pooled prevalence rates of 48%, 35%, and 21%, respectively. Conclusion: COVID-19 patients show various oral manifestations that may help clinicians identify the disease promptly. Recognition of the signs and symptoms of COVID-19 is critical for an early diagnosis and better prognosis.
Household secondary attack rates and risk factors during periods of SARS-CoV-2 Delta and Omicron variant predominance in the Republic of Korea
Jin Lee, Mijeong Ko, Seontae Kim, Dosang Lim, Gemma Park, Sang-Eun Lee
Osong Public Health Res Perspect. 2023;14(4):263-271.   Published online August 11, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0133
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The household secondary attack rate (SAR) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important indicator for community transmission. This study aimed to characterize transmission by comparing household SARs and identifying risk factors during the periods of Delta and Omicron variant predominance in Republic of Korea.
Methods
We defined the period of Delta variant predominance (Delta period) as July 25, 2021 to January 15, 2022, and the period of Omicron variant predominance (Omicron period) as February 7 to September 3, 2022. The number of index cases included was 214,229 for the Delta period and 5,521,393 for the Omicron period. To identify the household SARs and risk factors for each period, logistic regression was performed to determine the adjusted odds ratio (aOR).
Results
The SAR was 35.2% for the Delta period and 43.1% for the Omicron period. The aOR of infection was higher in 2 groups, those aged 0 to 18 years and ≥75 years, compared to those aged 19 to 49 years. Unvaccinated individuals (vs. vaccinated individuals) and individuals experiencing initial infection (vs. individuals experiencing a second or third infection) had an increased risk of infection with SARS-CoV-2.
Conclusion
This study analyzed the household SARs and risk factors. We hope that the results can help develop age-specific immunization plans and responses to reduce the SAR in preparation for emerging infectious diseases or potential new variants of SARS-CoV-2.
Risk factors for transmission in a COVID-19 cluster infection in a high school in the Republic of Korea
Jin-Hwan Jeon, Su Jin Kang, Se-Jin Jeong, Hyeon-Cheol Jang, Young-Joon Park, Sang-Eun Lee
Osong Public Health Res Perspect. 2023;14(4):252-262.   Published online July 27, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0125
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  • 1 Web of Science
  • 1 Crossref
Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study aimed to examine the scale, characteristics, risk factors, and modes of transmission in a coronavirus disease 2019 (COVID-19) outbreak at a high school in Seoul, Republic of Korea.
Methods
An epidemiological survey was conducted of 1,118 confirmed cases and close contacts from a COVID-19 outbreak at an educational facility starting on May 31, 2021. In-depth interviews, online questionnaires, flow evaluations, and CCTV analyses were used to devise infection prevention measures. Behavioral and spatial risk factors were identified, and statistical significance was tested.
Results
Among 3rd-year students, there were 33 confirmed COVID-19 cases (9.6%). Students who used a study room in the annex building showed a statistically significant 4.3-fold elevation in their relative risk for infection compared to those who did not use the study room. Moreover, CCTV facial recognition analysis confirmed that 17.8% of 3rd-year students did not wear masks and had the lowest percentage of mask-wearers by grade. The air epidemiological survey conducted in the study room in the annex, which met the 3 criteria for a closed space, confirmed that there was only 10% natural ventilation due to the poor ventilation system.
Conclusion
To prevent and manage the spread of COVID-19 in educational facilities, advance measures that consider the size, operation, and resources of each school are crucial. In addition, various survey methodologies should be used in future studies to quickly analyze a wider range of data that can inform an evidence-based quarantine response.

Citations

Citations to this article as recorded by  
  • Detection of a cluster of Omicron's BA.4 sublineage in Northern Senegal and identification of the first XAS recombinant variant in Senegal
    Martin Faye, Modeste Name Faye, Babacar Ndiaye, Moussa Moïse Diagne, Safietou Sankhe, Ndeye Marième Top, Amadou Diallo, Cheikh Loucoubar, Ndongo Dia, Amadou Alpha Sall, Ousmane Faye
    Virus Research.2024; 339: 199259.     CrossRef
Estimating the number of severe COVID-19 cases and COVID-19-related deaths averted by a nationwide vaccination campaign in Republic of Korea
Ji Hae Hwang, Ju Hee Lee, Eun Jung Jang, Ryu Kyung Kim, Kil Hun Lee, Seon Kyeong Park, Sang Eun Lee, Chungman Chae, Sangwon Lee, Young Joon Park
Osong Public Health Res Perspect. 2023;14(3):164-172.   Published online June 22, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0096
  • 1,426 View
  • 107 Download
  • 1 Web of Science
  • 1 Crossref
Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The Korea Disease Control and Prevention Agency promotes vaccination by regularly providing information on its benefits for reducing the severity of coronavirus disease 2019 (COVID-19). This study aimed to analyze the number of averted severe COVID-19 cases and COVID-19-related deaths by age group and quantify the impact of Republic of Korea’s nationwide vaccination campaign.
Methods
We analyzed an integrated database from the beginning of the vaccination campaign on February 26, 2021 to October 15, 2022. We estimated the cumulative number of severe cases and COVID-19-related deaths over time by comparing observed and estimated cases among unvaccinated and vaccinated groups using statistical modeling. We compared daily age-adjusted rates of severe cases and deaths in the unvaccinated group to those in the vaccinated group and calculated the susceptible population and proportion of vaccinated people by age.
Results
There were 23,793 severe cases and 25,441 deaths related to COVID-19. We estimated that 119,579 (95% confidence interval [CI], 118,901–120,257) severe COVID-19 cases and 137,636 (95% CI, 136,909–138,363) COVID-19-related deaths would have occurred if vaccination had not been performed. Therefore, 95,786 (95% CI, 94,659–96,913) severe cases and 112,195 (95% CI, 110,870–113,520) deaths were prevented as a result of the vaccination campaign.
Conclusion
We found that, if the nationwide COVID-19 vaccination campaign had not been implemented, the number of severe cases and deaths would have been at least 4 times higher. These findings suggest that Republic of Korea’s nationwide vaccination campaign reduced the number of severe cases and COVID-19 deaths.

Citations

Citations to this article as recorded by  
  • Comparative Effectiveness of COVID-19 Bivalent Versus Monovalent mRNA Vaccines in the Early Stage of Bivalent Vaccination in Korea: October 2022 to January 2023
    Ryu Kyung Kim, Young June Choe, Eun Jung Jang, Chungman Chae, Ji Hae Hwang, Kil Hun Lee, Ji Ae Shim, Geun-Yong Kwon, Jae Young Lee, Young-Joon Park, Sang Won Lee, Donghyok Kwon
    Journal of Korean Medical Science.2023;[Epub]     CrossRef
Brief Report
Temporal association between the age-specific incidence of Guillain-Barré syndrome and SARS-CoV-2 vaccination in Republic of Korea: a nationwide time-series correlation study
Hyunju Lee, Donghyok Kwon, Seoncheol Park, Seung Ri Park, Darda Chung, Jongmok Ha
Osong Public Health Res Perspect. 2023;14(3):224-231.   Published online June 22, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0050
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The incidence of Guillain-Barré syndrome (GBS) changed significantly during the coronavirus disease 2019 (COVID-19) pandemic. Emerging reports suggest that viral vector-based vaccines may be associated with an elevated risk of GBS.
Methods
In this nationwide time-series correlation study, we examined the age-specific incidence of GBS from January 2011 to August 2022, as well as data on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccinations and infections from February 2021 to August 2022. We compared the forecasted estimates of age-specific GBS incidence, using the pre-SARS-CoV-2 period as a benchmark, with the actual incidence observed during the post-vaccination period of the pandemic. Furthermore, we assessed the temporal association between GBS, SARS-CoV-2 vaccinations, and COVID-19 for different age groups.
Results
In the age group of 60 and older, the rate ratio was significantly elevated during June-August and November 2021. A significant, strong positive association was observed between viral vector-based vaccines and GBS incidence trends in this age group (r=0.52, p=0.022). For the 30 to 59 years age group, the rate ratio was notably high in September 2021. A statistically significant, strong positive association was found between mRNA-based vaccines and GBS incidence in this age group (r=0.61, p=0.006).
Conclusion
Viral vector-based SARS-CoV-2 vaccines were found to be temporally associated with an increased risk of GBS, particularly in older adults. To minimize age-specific and biological mechanism-specific adverse events, future vaccination campaigns should adopt a more personalized approach, such as recommending homologous mRNA-based SARS-CoV-2 vaccines for older adults to reduce the heightened risk of GBS.
Original Articles
The COVID-19 pandemic and healthcare utilization in Iran: evidence from an interrupted time series analysis
Monireh Mahmoodpour-Azari, Satar Rezaei, Nasim Badiee, Mohammad Hajizadeh, Ali Mohammadi, Ali Kazemi-Karyani, Shahin Soltani, Mehdi Khezeli
Osong Public Health Res Perspect. 2023;14(3):180-187.   Published online June 22, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0041
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study aimed to examine the effect of the coronavirus disease 2019 (COVID-19) outbreak on the hospitalization rate, emergency department (ED) visits, and outpatient clinic visits in western Iran.
Methods
We collected data on the monthly hospitalization rate, rate of patients referred to the ED, and rate of patients referred to outpatient clinics for a period of 40 months (23 months before and 17 months after the COVID-19 outbreak in Iran) from all 7 public hospitals in the city of Kermanshah. An interrupted time series analysis was conducted to examine the impact of COVID-19 on the outcome variables in this study.
Results
A statistically significant decrease of 38.11 hospitalizations per 10,000 population (95% confidence interval [CI], 24.93–51.29) was observed in the first month of the COVID-19 outbreak. The corresponding reductions in ED visits and outpatient visits per 10,000 population were 191.65 (95% CI, 166.63–216.66) and 168.57 (95% CI, 126.41–210.73), respectively. After the initial reduction, significant monthly increases in the hospitalization rate (an increase of 1.81 per 10,000 population), ED visits (an increase of 2.16 per 10,000 population), and outpatient clinic visits (an increase of 5.77 per 10,000 population) were observed during the COVID-19 pandemic.
Conclusion
Our study showed that the utilization of outpatient and inpatient services in hospitals and clinics significantly declined after the COVID-19 outbreak, and use of these services did not return to pre-outbreak levels as of June 2021.
Results of contact tracing for SARS-CoV-2 Omicron sub-lineages (BA.4, BA.5, BA.2.75) and the household secondary attack risk
Mi Yu, Sang-Eun Lee, Hye Young Lee, Hye-jin Kim, Yeong-Jun Song, Jian Jeong, Ae Kyung Park, Il-Hwan Kim, Eun-jin Kim, Young-Joon Park
Osong Public Health Res Perspect. 2023;14(3):173-179.   Published online June 22, 2023
DOI: https://doi.org/10.24171/j.phrp.2022.0285
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study aimed to assess the contact tracing outcomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron sub-lineages BA.4, BA.5, and BA.2.75 within Republic of Korea, and to generate foundational data for responding to future novel variants.
Methods
We conducted investigations and contact tracing for 79 confirmed BA.4 cases, 396 confirmed BA.5 cases, and 152 confirmed BA.2.75 cases. These cases were identified through random sampling of both domestically confirmed and imported cases, with the goal of evaluating the pattern of occurrence and transmissibility.
Results
We detected 79 instances of Omicron sub-lineage BA.4 across a span of 46 days, 396 instances of Omicron sub-lineage BA.5 in 46 days, and 152 instances of Omicron sub-lineage BA.2.75 over 62 days. One patient with severe illness was confirmed among the BA.5 cases; however, there were no reports of severe illness in the confirmed BA.4 and BA.2.75 cases. The secondary attack risk among household contacts were 19.6% for BA.4, 27.8% for BA.5, and 24.3% for BA.2.75. No statistically significant difference was found between the Omicron sub-lineages.
Conclusion
BA.2.75 did not demonstrate a higher tendency for transmissibility, disease severity, or secondary attack risk within households when compared to BA.4 and BA.5. We will continue to monitor major SARS-CoV-2 variants, and we plan to enhance the disease control and response systems.
Vaccine effectiveness and the epidemiological characteristics of a COVID-19 outbreak in a tertiary hospital in Republic of Korea
Seonhee Ahn, Tae Jong Son, Yoonsuk Jang, Jihyun Choi, Young Joon Park, Jiseon Seong, Hyun Hee Kwon, Muk Ju Kim, Donghyok Kwon
Osong Public Health Res Perspect. 2023;14(3):188-196.   Published online June 8, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0066
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
Healthcare facilities are high-risk sites for infection. This study analyzed the epidemiological characteristics of a coronavirus disease 2019 (COVID-19) outbreak in a tertiary hospital after COVID-19 vaccination had been introduced in Republic of Korea. Vaccine effectiveness (VE) and shared anti-infection strategies are also assessed.
Methods
The risk levels for 4,074 contacts were evaluated. The epidemiological characteristics of confirmed cases were evaluated using the chi-square test. The “1 minus relative risk” method was used to determine VE in preventing infection, progression to severe disease, and death. In the largest affected area (the 8th floor), a separate relative risk analysis was conducted. A multivariate logistic regression analysis (with 95% confidence interval [CIs]) was used to identify transmission risk factors with a significance level <10% via the backward elimination method.
Results
In total, 181 cases of COVID-19 were confirmed, with an attack rate of 4.4%. Of those cases, 12.7% progressed to severe disease, and 8.3% died. In the cohort isolation area on the 8th floor, where 79.0% of the confirmed cases occurred, the adjusted odds ratio was 6.55 (95% CI, 2.99–14.33) and 2.19 (95% CI, 1.24–3.88) for caregivers and the unvaccinated group, respectively. VE analysis revealed that 85.8% of the cases that progressed to severe disease and 78.6% of the deaths could be prevented by administering a second vaccine.
Conclusion
Caregiver training for infection prevention and control is necessary to reduce infection risk. Vaccination is an important intervention to reduce the risk of progression to severe disease and death.
Risk factors for COVID-19 outbreaks in livestock slaughtering and processing facilities in Republic of Korea
Seongju Choi, Tae Jong Son, Yeon-Kyung Lee
Osong Public Health Res Perspect. 2023;14(3):207-218.   Published online June 8, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0035
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
The goal of this study was to help prevent and control the spread of coronavirus disease 2019 (COVID-19) by identifying transmission routes and risk factors in livestock slaughtering and processing facilities (SPFs) and establishing an optimal intervention strategy for outbreaks.
Methods
This case series study was a demographic analysis of patients with confirmed COVID-19 associated with 5 SPFs in Korea between January and June 2021. Additionally, in a retrospective cohort study, the association between COVID-19 infection and risk factors was analyzed for SPFs at which outbreaks occurred.
Results
The COVID-19 attack rates were 11.2%, 24.5%, and 6.8% at 3 poultry SPFs (PSPFs) and 15.5% and 25.2% at 2 mammal SPFs (MSPFs). Regarding spatial risk factors, the COVID-19 risk levels were 12.1-, 5.2-, and 5.0-fold higher in the refrigeration/ freezing, by-product processing, and carcass cutting areas, respectively, than in the office area. The risk of COVID-19 infection was 2.1 times higher among employees of subcontractors than among employees of contractors. The COVID-19 risk levels were 5.3- and 3.0-fold higher in foreign workers than in native Korean workers in the PSPFs and MSPFs, respectively.
Conclusion
As the COVID-19 pandemic continues, a detailed policy for infectious disease prevention and control intervention is needed, without interrupting economic activities. Thus, we propose an ideal intervention plan to prevent COVID-19 through disinfection and preemptive testing and to block its transmission through effective contact management during outbreaks at SPFs.
Short Communication
Correlations between regional characteristics of counties and the ratio of intracounty to extracounty sources of COVID-19 in Gangwon Province, Republic of Korea
Seungmin Jeong, Chaeyun Lim, Sunhak Bae, Youngju Nam, Eunmi Kim, Myeonggi Kim, Saerom Kim, Yeojin Kim
Osong Public Health Res Perspect. 2023;14(3):219-223.   Published online June 8, 2023
DOI: https://doi.org/10.24171/j.phrp.2023.0014
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Graphical AbstractGraphical Abstract AbstractAbstract PDF
Objectives
This study aimed to examine the correlations between the regional characteristics of counties in Gangwon Province, Republic of Korea and the ratio of intracounty to extracounty sources of coronavirus disease 2019 (COVID-19) infection.
Methods
The region of the infectious contact was analysed for each COVID-19 case reported in Gangwon Province between February 22, 2020 and February 7, 2022. The population, population density, area, the proportion of urban residents, the proportion of older adults (>65 years), financial independence, and the number of adjacent counties were assessed for each of the 18 counties in Gangwon Province. Correlation coefficients between regional characteristics and the ratio of intracounty to extracounty infections were calculated.
Results
In total, 19,645 cases were included in this study. The population, population density, proportion of older adults, and proportion of urban residents were significantly correlated with the ratio of intracounty to extracounty infections. A stratified analysis with an age cut-point of 65 years showed that the proportion of older adults had a significant negative correlation with the ratio of intracounty to extracounty infections. In other words, the proportions of extracounty infections were higher in countries with higher proportions of older adults.
Conclusion
Regions with ageing populations should carefully observe trends in infectious disease outbreaks in other regions to prevent possible transmission.

PHRP : Osong Public Health and Research Perspectives