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South Korea implemented interventions to curb the spread of the novel coronavirus disease 2019 (COVID-19) pandemic with discovery of the first case in early 2020. Mathematical modeling designed to reflect the dynamics of disease transmission has been shown to be an important tool for responding to COVID-19. This study aimed to review publications on the structure, method, and role of mathematical models focusing on COVID-19 transmission dynamics in Korea. In total, 42 papers published between August 7, 2020 and August 21, 2022 were studied and reviewed. This study highlights the construction and utilization of mathematical models to help craft strategies for predicting the course of an epidemic and evaluating the effectiveness of control strategies. Despite the limitations caused by a lack of available epidemiological and surveillance data, modeling studies could contribute to providing scientific evidence for policymaking by simulating various scenarios.
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Purpose@#The strategy of latent tuberculosis infection (LTBI) treatment in household tuberculosis (TB) contacts has been expanding in South Korea. However, there is little evidence of the cost-effectiveness of LTBI treatment in patients over 35 years of age. This study aimed to evaluate the cost-effectiveness of LTBI treatment among household TB contacts in different age groups in South Korea. @*Materials and Methods@#An age-structured model of TB was developed based on the reports from the Korea Disease Control and Prevention Agency and the National Health Insurance Service. Quality-adjusted life-years (QALY) and the averted number of TBrelated deaths were estimated along with discounted costs for a measure of incremental cost-effectiveness ratios. @*Results@#The number of cumulative active TB cases would decrease by 1564 and 7450 under the scenario of LTBI treatment for those aged <35 years and <70 years, respectively, relative to the no-treatment scenario. The treatment strategies for patients aged 0 to <35 years, <55 years, <65 years, and <70 years would add 397, 1482, 3782, and 8491 QALYs at a cost of $660, $5930, $4560, and $2530, respectively, per QALY. For the averted TB-related deaths, LTBI treatment targeting those aged 0 to <35 years, <55 years, <65 years, and <70 years would avert 7, 89, 155, and 186 deaths at a cost of $35900, $99200, $111100, and $115700 per deaths, respectively, in 20 years. @*Conclusion@#The age-specific expansion policy of LTBI treatment not only for those under 35 years of age but also for those under 65 years of age among household contacts was cost-effective in terms of QALYs and averted TB deaths.
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Purpose@#Adult Korean men belonging to the main economically active population are known to have long sedentary hours. This study was undertaken to determine the difference and relevance of sedentary hours on the nutrition, diet, and health status of adult men, and to suggest how to prevent health risk factors. @*Methods@#Subjects (n = 1,068) were classified into 4 groups based on their sedentary hours, ranging from the first quartile (Q1) having the least hours spent sitting, to the fourth quartile (Q4) spending the longest hours. @*Results@#Subjects belonging to Q4 had the lowest average age, the largest waist circumference, and the highest level of education. Among those engaged in economic activities, the ratio of white-collar workers was significantly higher in Q4. Accordingly, the rate of not doing high-intensity or moderate-intensity physical activity while working was also the highest in Q4. A significant difference was obtained in the drinking frequency between groups, but this was found to be associated with the average working hours rather than sedentary hours. The proportion of not doing aerobic exercise was higher with longer sitting hours. The highest diagnosis of diabetes (8.8%) was obtained in the Q4 group. Among the factors related to cardiovascular disease, only low density lipoprotein-cholesterol showed a significant difference, with Q4 being significantly higher than Q1. Considering energy and nutrient intake, vitamin B 1 and calcium intake were the lowest in the group with the longest sitting hours, as well as the least consumption of vitamin C than the recommended estimated average requirement. @*Conclusion@#The results of this study suggest that the health and nutritional status of Korean adult men are affected by sedentary hours. This should be recognized as a health risk factor and guidelines need to be developed for sedentary lifestyle management.
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Purpose@#This study examined the demographics, health status, dietary habits, energy, nutrient intake, and protein intake based on levels of inclusion of animal food among females in their 20s by using data from the 7th Korea National Health and Nutrition Examination Survey. @*Methods@#The subjects (n = 912) were divided into 4 groups according to the frequency of animal foods consumed which were categorized as meat, seafood, eggs, and dairy products, or other animal-derived foods. @*Results@#The subjects with a lower frequency of animal food intake ate out less frequently.As the frequency of animal food intake decreased, the total energy intake too decreased with higher carbohydrate and lower protein intake ratios. In the low frequency of animal food intake group, a higher proportion of subjects had energy intake below the estimated energy requirement and the intake of protein, vitamin B 1 , vitamin B 2 , niacin, calcium, phosphorus, and iron were below the estimated average requirements. The average protein intake was more than the recommended 45 g in all four groups. However, the lower the frequency of animal food intake, the higher the proportion of people having lower protein intake compared to the recommended intake of 0.91 g per kg body weight. It became apparent that people who do not consume animal foods at all did not meet the recommended levels of protein intake. Thus, people pursuing a vegan diet may be at risk of low protein intake. @*Conclusion@#This study suggests that economic characteristics, dietary habits, energy, and nutrient intake are affected by the frequency of animal food consumed, or in other words, by the degree of vegetable-centered diet. Thus, this study would help improve the perception of vegetarianism, develop individualized dietary guidance and nutrition education programs for people practicing vegan or vegetarian diets to ensure that they have a balanced diet.
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Background@#Plasmodium vivax malaria has a persistent liver stage that causes relapse, and introducing tafenoquine to suppress relapse could aid in disease eradication. Therefore, we assessed the impact of tafenoquine introduction on P. vivax malaria incidence and performed a cost-benefit analysis from the payer’s perspective. @*Methods@#We expanded the previously developed P. vivax malaria dynamic transmission model and calibrated it to weekly civilian malaria incidences in 2014–2018. Primaquine and tafenoquine scenarios were considered by assuming different relapse probabilities, and relapse and total P. vivax malaria cases were predicted over the next decade for each scenario. We then estimated the number of cases prevented by replacing primaquine with tafenoquine. The cost and benefit of introducing tafenoquine were obtained using medical expenditure from a nationwide database, and a cost-benefit analysis was conducted. A probabilistic sensitivity analysis was performed to assess the economic feasibility robustness of tafenoquine introduction under uncertainties of model parameters, costs, and benefits. @*Results@#Under 0.04 primaquine relapse probability, the introduction of tafenoquine with relapse probability of 0.01 prevented 129 (12.27%) and 35 (77.78%) total and relapse cases, respectively, over the next decade. However, under the same relapse probability as primaquine, introducing tafenoquine had no additional preventative effect. The 14-day primaquine treatment cost was $3.71. The tafenoquine and the glucose-6-phosphate dehydrogenase rapid diagnostic testing cost $57.37 and $7.76, totaling $65.13. The average medical expenditure per malaria patient was estimated at $1444.79. The cost-benefit analysis results provided an incremental benefit-cost ratio (IBCR) from 0 to 3.21 as the tafenoquine relapse probability decreased from 0.04 to 0.01. The probabilistic sensitivity analysis showed an IBCR > 1, indicating that tafenoquine is beneficial, with a probability of 69.1%. @*Conclusion@#Tafenoquine could reduce P. vivax malaria incidence and medical costs and bring greater benefits than primaquine.
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Purpose@#To evaluate the efficacy of intervention policies on coronavirus disease-19 (COVID-19) dissemination. @*Materials and Methods@#An age-structured compartmental model for the COVID-19 outbreak was proposed to predict the impact of control measures in the Seoul/Gyeonggi region. The model was calibrated based on actual data and realistic situations, including daily vaccine doses, proportion of delta variant cases, and confirmed cases by age. We simulated different scenarios for non-pharmaceutical interventions by varying social distancing and school attendance strategies. @*Results@#Two-step mitigation of social distancing without in-person classes would result in a rapid increase in confirmed cases up to 10000 but would keep severe cases within the manageable range of the health care system. The overall impact of taking down the distancing level by one step with twice the increase in contacts at school was comparable to the above scenario. Implementation of two-step mitigation of social distancing along with a two-fold increase in contacts among the school-age group would dramatically increase confirmed and severe cases by over 80000 and 100, respectively, as early as the beginning of December. This policy would cause the situation to spiral out of control, considering the scale of the response and time to prepare. On the other hand, the burden on the current healthcare system caused by two-step mitigation of social distancing and 40% increased contacts in the school-age group was manageable if prepared. @*Conclusion@#A compromise between social distancing and school attendance policy and timely preparations for the spread of COVID-19 are required.
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Purpose@#This study examined general characteristics, health status, accessibility to medical services, health-related quality of life, dietary behavior, and energy and nutrient intakes of the elderly at different levels of food security utilizing data from the 7th Korea National Health and Nutrition Examination Survey (2016–2018). @*Methods@#The elderly subjects (1,721 males and 2,271 females) were divided into 3 groups (secure, mildly insecure, moderately/severely insecure) according to their food security levels. Health and nutrient status was determined using energy intake, nutrient density, the prevalence of insufficient nutrient intake, dietary behavior, and health status. @*Results@#The elderly with food insecurities had a lower self-evaluated health status and a higher prevalence of physician-diagnosed chronic diseases such as arthritis, osteoarthritis, rheumatoid arthritis, osteoporosis for males, and hypertension, stroke, arthritis, and osteoarthritis for females. The associated financial burden was the major reason for not accessing medical services in the food insecure group. Furthermore, the food insecure group had a higher risk of impaired health-related quality of life compared to the secure group. The proportion of subjects with an energy intake below the estimated energy requirement was higher in the food insecure group and a significantly higher prevalence of insufficient intake was observed for all the nutrients (proteins, vitamin A, vitamin B 1 , vitamin B 2 , niacin, vitamin C, calcium, and iron) assessed in this study compared to the food secure group. @*Conclusion@#This study suggests that food insecurity poses a challenge to the health and nutritional status of the elderly population in Korea and needs proper management. It would be helpful to develop food and nutrition assistance programs to ensure the food stability of the elderly population and assure quality to address gaps in their nutrient intake.
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Metformin, a first-line drug for type 2 diabetes mellitus, has been recognized as a potential anti-tumor agent in recent years. Epigallocatechin-3-gallate (EGCG), as the dominant catechin in green tea, is another promising adjuvant agent for tumor prevention. In the present work, the potential effect of EGCG on the anti-tumor efficacy of metformin in a mouse melanoma cell line (B16F10) was investigated. Results indicated that EGCG and metformin exhibited a synergistic effect on cell viability, migration, and proliferation, as well as signal transducer and activator of transcription 3/nuclear factor-κB (STAT3/NF-κB) pathway signaling and the production of inflammation cytokines. Meanwhile, the combination showed an antagonistic effect on cell apoptosis and oxidative stress levels. The combination of EGCG and metformin also differentially affected the nucleus (synergism) and cytoplasm (antagonism) of B16F10 cells. Our findings provide new insight into the potential effects of EGCG on the anti-tumor efficacy of metformin in melanoma cells.
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OBJECTIVES: The pandemic of novel influenza A (H1N1) virus has required decision-makers to act in the face of the substantial uncertainties. In this study, we evaluated the potential impact of the pandemic response strategies in the Republic of Korea using a mathematical model. METHODS: We developed a deterministic model of a pandemic (H1N1) 2009 in a structured population using the demographic data from the Korean population and the epidemiological feature of the pandemic (H1N1) 2009. To estimate the parameter values for the deterministic model, we used the available data from the previous studies on pandemic influenza. The pandemic response strategies of the Republic of Korea for novel influenza A (H1N1) virus such as school closure, mass vaccination (70% of population in 30 days), and a policy for anti-viral drug (treatment or prophylaxis) were applied to the deterministic model. RESULTS: The effect of two-week school closure on the attack rate was low regardless of the timing of the intervention. The earlier vaccination showed the effect of greater delays in reaching the peak of outbreaks. When it was no vaccination, vaccination at initiation of outbreak, vaccination 90 days after the initiation of outbreak and vaccination at the epidemic peak point, the total number of clinical cases for 400 days were 20.8 million, 4.4 million, 4.7 million and 12.6 million, respectively. The pandemic response strategies of the Republic of Korea delayed the peak of outbreaks (about 40 days) and decreased the number of cumulative clinical cases (8 million). CONCLUSIONS: Rapid vaccination was the most important factor to control the spread of pandemic influenza, and the response strategies of the Republic of Korea were shown to delay the spread of pandemic influenza in this deterministic model.