KCDC Risk Assessments on the Initial Phase of the COVID-19 Outbreak in Korea.

OBJECTIVES: This study aims to evaluate the risk assessments of coronavirus 2019 (COVID-19) in the Korea Centers for Disease Control and Prevention (KCDC), from the point of detection to the provision of basic information to the relevant public health authorities. METHODS: To estimate the overall risk of specific public health events, probability, and impact at the country-level were evaluated using available information. To determine the probability of particular public health events, the risk of importation and risk of transmission were taken into consideration. KCDC used 5 levels ("very low," "low," "moderate," "high," and "very high") for each category and overall risk was eventually decided. RESULTS: A total of 8 risk assessments were performed on 8 separate occasions between January 8th to February 28th, 2020, depending on the detection and report of COVID-19 cases in other countries. The overall risk of the situation in each assessment increased in severity over this period: "low" (first), "moderate" (second), "high" (third), "high" (fourth), "high" (fifth), "high" (sixth), "high" (seventh), and "very high" (eighth). CONCLUSION: The KCDC's 8 risk assessments were utilized to activate national emergency response mechanisms and eventually prepare for the pandemic to ensure the containment and mitigation of COVID-19 with non-pharmaceutical public health measures.

Characteristics of HIV seroprevalence of visitors to public health centers under the national HIV surveillance system in Korea: cross sectional study.

BACKGROUND: In Korea, the cumulative number of HIV-infected individuals was smaller than those of other countries. Mandatory HIV tests, dominating method until 1990's, have been gradually changed to voluntary HIV tests. We investigated HIV seroprevalence status and its characteristics of visitors to Public Health Centers (PHCs), which conducted both mandatory test and voluntary test under the national HIV/STI surveillance program. METHODS: We used HIV-testing data from 246 PHCs in 2005 through the Health Care Information System. The number of test taker was calculated using the code distinguished by the residential identification number. The subjects were classified into four groups by reason for testing; General group, HIV infection suspected group (HIV ISG), HIV test recommended group (HIV TRG), and sexually transmitted infection (STI) risk group. RESULTS: People living with HIV/AIDS were 149 (124 male and 25 female) among 280,456 individuals tested at PHCs. HIV seroprevalence was 5.3 per 10,000 individuals. Overall, the male revealed significantly higher seroprevalence than the female (adjusted Odds Ratio (adj. OR): 6.2; CI 3.8-10.2). Individuals aged 30-39 years (adj. OR: 2.6; CI 1.7-4.0), and 40-49 years (adj. OR: 3.8; CI 2.4-6.0) had higher seroprevalence than 20-29 years. Seroprevalence of HIV ISG (voluntary test takers and cases referred by doctors) was significantly higher than those of others. Foreigners showed higher seroprevalence than native Koreans (adj. OR: 3.8; CI 2.2-6.4). HIV ISG (adj. OR: 4.9; CI 3.2-7.5), and HIV TRG (adj. OR: 2.6; CI 1.3-5.4) had higher seroprevalence than General group. CONCLUSION: A question on the efficiency of current mandatory test is raised because the seroprevalence of mandatory test takers was low. However, HIV ISG included voluntary test takers was high in our result. Therefore, we suggest that Korea needs to develop a method encouraging more people to take voluntary tests at PHCs, also to expand the anonymous testing centers and Voluntary Counselling and Testing Program (VCT) for general population to easily access to HIV testing.

Estimation of the Size of Dengue and Zika Infection Among Korean Travelers to Southeast Asia and Latin America, 2016-2017.

OBJECTIVES: To estimate the number and risk of imported infections resulting from people visiting Asian and Latin American countries. METHODS: The dataset of visitors to 5 Asian countries with dengue were analyzed for 2016 and 2017, and in the Philippines, Thailand and Vietnam, imported cases of zika virus infection were also reported. For zika virus, a single imported case was reported from Brazil in 2016, and 2 imported cases reported from the Maldives in 2017. To understand the transmissibility in 5 Southeast Asian countries, the estimate of the force of infection, i.e., the hazard of infection per year and the average duration of travel has been extracted. Outbound travel numbers were retrieved from the World Tourism Organization, including business travelers. RESULTS: The incidence of imported dengue in 2016 was estimated at 7.46, 15.00, 2.14, 4.73 and 2.40 per 100,000 travelers visiting Philippines, Indonesia, Thailand, Malaysia and Vietnam, respectively. Similarly, 2.55, 1.65, 1.53, 1.86 and 1.70 per 100,000 travelers in 2017, respectively. It was estimated that there were 60.1 infections (range: from 16.8 to 150.7 infections) with zika virus in Brazil, 2016, and 345.6 infections (range: from 85.4 to 425.5 infections) with zika virus in the Maldives, 2017. CONCLUSION: This study emphasizes that dengue and zika virus infections are mild in their nature, and a substantial number of infections may go undetected. An appropriate risk assessment of zika virus infection must use the estimated total size of infections.

Inverse relationship between viral load and genotypic resistance mutations in Korean patients with primary HIV type 1 infections.

The transmission of antiretroviral-resistant HIV-1 strains is associated with suboptimal virological responses to initial antiretroviral therapy. However, certain types of resistance mutations are known to be associated with decreased viral fitness, which confers a lower replication capacity than that of the wild-type virus in the absence of antiretroviral drugs. Therefore, we evaluated the relationship between antiretroviral resistance mutations and viral replication in the primary HIV-1 infection (PHI) period. From January 2002 to March 2005, 52 PHI patients were identified in the Republic of Korea. HIV-1 RNA genotyping was performed, and the resistance mutation score was obtained from the HIV Drug Resistance Database of Stanford University. We defined the sum of the average resistance mutation scores (SARMS) for each antiretroviral drug class as a measure of the degree of resistance of any specific strain. The overall mean SARMS was 2.00 +/- 2.74, and the annual mean did not change significantly during the study period. No critical resistance mutation gene was identified in the study group. The SARMS showed a weak negative correlation with the viral load log10 during PHI, but without statistical significance (r = -0.274, p = 0.051). But the mean SARMS of patients with a viral load exceeding 100,000 copies/ml was significantly lower than that of patients with a viral load of less than 100,000 copies/ml (p = 0.03). Evaluation of the potency of antiretroviral resistance revealed a weak negative correlation with viral replication in the PHI period. This could be one reason why the transmission of resistant strains in PHI patients is not increasing significantly despite the widespread use of highly active antiretroviral therapy (HAART).

The Characteristics of Middle Eastern Respiratory Syndrome Coronavirus Transmission Dynamics in South Korea.

OBJECTIVES: The outbreak of Middle Eastern respiratory syndrome coronavirus (MERS-CoV) was one of the major events in South Korea in 2015. In particular, this study pays attention to formulating a mathematical model for MERS transmission dynamics and estimating transmission rates. METHODS: Incidence data of MERS-CoV from the government authority was analyzed for the first aim and a mathematical model was built and analyzed for the second aim of the study. A mathematical model for MERS-CoV transmission dynamics is used to estimate the transmission rates in two periods due to the implementation of intensive interventions. RESULTS: Using the estimates of the transmission rates, the basic reproduction number was estimated in two periods. Due to the superspreader, the basic reproduction number was very large in the first period; however, the basic reproduction number of the second period has reduced significantly after intensive interventions. CONCLUSION: It turned out to be the intensive isolation and quarantine interventions that were the most critical factors that prevented the spread of the MERS outbreak. The results are expected to be useful to devise more efficient intervention strategies in the future.

Assessment of intensive vaccination and antiviral treatment in 2009 influenza pandemic in Korea.

OBJECTIVES: We characterized and assessed public health measures, including intensive vaccination and antiviral treatment, implemented during the 2009 influenza pandemic in the Republic of Korea. METHODS: A mathematical model for the 2009 influenza pandemic is formulated. The transmission rate, the vaccination rate, the antiviral treatment rate, and the hospitalized rate are estimated using the least-squares method for the 2009 data of the incidence curves of the infected, vaccinated, treated, and hospitalized. RESULTS: The cumulative number of infected cases has reduced significantly following the implementation of the intensive vaccination and antiviral treatment. In particular, the intensive vaccination was the most critical factor that prevented severe outbreak. CONCLUSION: We have found that the total infected proportion would increase by approximately six times under the half of vaccination rates.

A Study on the Characteristics of Infrequent and Frequent Outpatients Visiting Korean Traditional Medical Facilities.

OBJECTIVES: This study was intended to analyze the characteristics of infrequent and frequent outpatients visiting Korean medical facilities, and find the related variables of frequent users. METHODS: The data source was the Report on the Usage and Consumption of Korean Medicine (2011) published by the Ministry of Health and Welfare and Korea Institute for Health and Social Affairs. We analyzed outpatient data using SAS 9.2. RESULTS: As much as 46.6% of the patients used Korean medical services over 11 times in 3 months. The proportion of frequent users increased depending on age, and their proportion was high in the low-income and low-education group. People with musculoskeletal disease, stroke, hypertension, and obesity were more likely to use Korean medical services. In general, patients were satisfied with their treatment, with frequent outpatients being more satisfied than infrequent outpatients. In logistic regression analysis, age and musculoskeletal disease were significant determinants of frequency of use of Korean medical services. CONCLUSION: Age, musculoskeletal disease, and specific diseases were highly associated with frequent Korean medical utilization.

A study of high-risk drinking patterns among generations based on the 2009 Korea national health and nutrition examination survey.

OBJECTIVES: The aim of this study was to identify how the drinking patterns of a generation on the paternal side affect those of the next generations by estimating the number of high-risk drinkers by generation according to the Alcohol Use Disorder Identification Test. METHODS: Data were selected from the 2009 Korea National Health and Nutrition Examination Survey conducted by the Korea Centers for Disease Control and Prevention and were analyzed using SPSS 18.0. RESULTS: Later generations started drinking earlier (62.4%, 71.8% and 91.1%, respectively). The majority of the second generation consumed more than 2-4 drinks a month (83.7%), but only a small proportion experienced difficulty in everyday life (9.6%), felt repentance (9.6%), or experienced memory loss (17.9%) after drinking. Unmarried third-generation adults with high-risk-drinking fathers reported more frequent alcohol consumption [odds ratio (OR) 1.441), greater amounts on one occasion (>7 cups for men, OR 1.661; > 5 cups for women, OR 2.078), temperance failure (OR 2.377), and repentance after drinking (OR 1.577). Unmarried third-generation adults with high-risk-drinking grandfathers consumed greater amounts of alcohol on one occasion (OR 3.642), and unmarried third-generation women more frequently consumed large amounts of alcohol (>5 cups, OR 4.091). Unmarried third-generation adults with high-risk-drinking fathers were more likely to exhibit high-risk drinking patterns (OR 1.608). Second-generation individuals from a high-risk-drinking first generation were more likely to engage in high-risk drinking (OR 3.705). CONCLUSION: High-risk drinking by a generation significantly affects the high-risk drinking patterns of subsequent generations.

Trends and Characteristics of HIV Infection among Suspected Tuberculosis Cases in Public Health Centers in Korea: 2001-2013.

OBJECTIVES: The Republic of Korea reports approximately 35,000 new tuberculosis (TB) patients each year, and the number of HIV-infected individuals is steadily increasing. Public health centers (PHCs) conduct TB diagnosis and treatment for risk groups in communities. This study aimed to identify possible trends and characteristics of HIV infection among suspected TB cases in PHCs. METHODS: Study subjects were suspected TB cases in PHCs who agreed to be tested for HIV from 2001 to 2013. Trends in HIV seroprevalence were assessed through a series of annual cross-sectional analyses. We analyzed suspected TB cases, and HIV-infected individuals among suspected TB cases, by gender, age, nationality, and region. RESULTS: The number of suspected tuberculosis cases who took an HIV test in PHCs was approximately 6,000 each year from 2001 to 2013. Among the suspected TB cases who took an HIV test, the number of those aged 20-39 is gradually decreasing, while the number of those aged 50-69 is increasing. During this period, 32 HIV-infected individuals were identified; the majority were men (94%), aged 30-49 (68%), Korean (94%), and residents in a metropolitan area (53%). HIV seroprevalence decreased from 8.2 per 10,000 persons in 2001 to 1.9 per 10,000 persons in 2013. CONCLUSION: This study has identified trends and characteristics of HIV infection among suspected tuberculosis cases in PHCs. This national data provides a basis for public health policy for HIV and tuberculosis infections.

Spatial distribution analysis of scrub typhus in Korea.

OBJECTIVE: This study analyzes the spatial distribution of scrub typhus in Korea. METHODS: A spatial distribution of Orientia tsutsugamushi occurrence using a geographic information system (GIS) is presented, and analyzed by means of spatial clustering and correlations. RESULTS: The provinces of Gangwon-do and Gyeongsangbuk-do show a low incidence throughout the year. Some districts have almost identical environmental conditions of scrub typhus incidence. The land use change of districts does not directly affect the incidence rate. CONCLUSION: GIS analysis shows the spatial characteristics of scrub typhus. This research can be used to construct a spatial-temporal model to understand the epidemic tsutsugamushi.

Forecasting the number of human immunodeficiency virus infections in the korean population using the autoregressive integrated moving average model.

OBJECTIVES: From the introduction of HIV into the Republic of Korea in 1985 through 2012, 9,410 HIV-infected Koreans have been identified. Since 2000, there has been a sharp increase in newly diagnosed HIV-infected Koreans. It is necessary to estimate the changes in HIV infection to plan budgets and to modify HIV/AIDS prevention policy. We constructed autoregressive integrated moving average (ARIMA) models to forecast the number of HIV infections from 2013 to 2017. METHODS: HIV infection data from 1985 to 2012 were used to fit ARIMA models. Akaike Information Criterion and Schwartz Bayesian Criterion statistics were used to evaluate the constructed models. Estimation was via the maximum likelihood method. To assess the validity of the proposed models, the mean absolute percentage error (MAPE) between the number of observed and fitted HIV infections from 1985 to 2012 was calculated. Finally, the fitted ARIMA models were used to forecast the number of HIV infections from 2013 to 2017. RESULTS: The fitted number of HIV infections was calculated by optimum ARIMA (2,2,1) model from 1985-2012. The fitted number was similar to the observed number of HIV infections, with a MAPE of 13.7%. The forecasted number of new HIV infections in 2013 was 962 (95% confidence interval (CI): 889-1,036) and in 2017 was 1,111 (95% CI: 805-1,418). The forecasted cumulative number of HIV infections in 2013 was 10,372 (95% CI: 10,308-10,437) and in 2017 was14,724 (95% CI: 13,893-15,555) by ARIMA (1,2,3). CONCLUSION: Based on the forecast of the number of newly diagnosed HIV infections and the current cumulative number of HIV infections, the cumulative number of HIV-infected Koreans in 2017 would reach about 15,000.

Public health crisis preparedness and response in Korea.

Since the 2006 Pandemic Influenza Preparedness and Response Plan according to the World Health Organization's recommendation, the Republic of Korea has prepared and periodically evaluated the plan to respond to various public health crises including pandemic influenza. Korea has stockpiled 13,000,000 doses of antiviral drugs covering 26% of the Korean population and runs 519 isolated beds in 16 medical institutions. The division of public health crisis response in Korea Centers for Disease Control and Prevention are in charge of responding to public health crises caused by emerging infectious diseases including severe acute respiratory syndrome, avian influenza human infection, and pandemic influenza. Its job description includes preparing for emerging infectious diseases, securing medical resources during a crisis, activating the emergency response during the crisis, and fortification of capabilities of public health personnel. It could evolve into a comprehensive national agency to deal with public health crisis based on the experience of previous national emerging infectious diseases.

Introduction of the Republic of Korea-the United States of America's Joint Exercise Against Biothreats in 2013: Able Response 13.

The Republic of Korea (ROK) and the the United States of America (USA) has held joint exercises to respond to biothreats in the Korean Peninsula since 2011. The exercise was called Able Response (AR) and it aims to coordinate interministerial procedures inside Korea and international procedures in requesting the medical resources urgently between ROK and USA, and among ROK and the United Nations, and nongovernmental organizations. AR13 was a functional exercise with a scenario that presumed a series of attack by terrorists, dispersing Bacillus anthracis in Seoul. The participants conducted exercises with action cells and using point-to-point communication system. It was followed by Senior Leadership Seminar participated by high-ranking officials in ROK and USA to discuss possible collaboration in advance. AR and its following actions will fortify collaboration between ROK and USA and enhance the capability of countermeasures against biothreats in Korea.

Are there spatial and temporal correlations in the incidence distribution of scrub typhus in Korea?

OBJECTIVES: A hierarchical generalized linear model (HGLM) was applied to estimate the transmission pattern of scrub typhus from 2001 to 2011 in the Republic of Korea, based on spatial and temporal correlation. METHODS: Based on the descriptive statistics of scrub typhus incidence from 2001 to 2011 reported to the Korean Centers for Disease Control and Prevention, the spatial and temporal correlations were estimated by HGLM. Incidences according to age, sex, and year were also estimated by the best-fit model out of nine HGLMs. A disease map was drawn to view the annual regional spread of the disease. RESULTS: The total number of scrub typhus cases reported from 2001 to 2011 was 51,136: male, 18,628 (36.4%); female, 32,508 (63.6%). The best-fit model selected was a combination of the spatial model (Markov random-field model) and temporal model (first order autoregressive model) of scrub typhus transmission. The peak incidence was 28.80 per 100,000 persons in early October and the peak incidence was 40.17 per 100,000 persons in those aged 63.3 years old by the best-fit HGLM. The disease map showed the spread of disease from the southern central area to a nationwide area, excepting Gangwon-do (province), Gyeongsangbuk-do (province), and Seoul. CONCLUSION: In the transmission of scrub typhus in Korea, there was a correlation to the incidence of adjacent areas, as well as that of the previous year. According to the disease map, we are unlikely to see any decrease in the incidence in the near future, unless ongoing aggressive measures to prevent the exposure to the vector, chigger mites, in rural areas, are put into place.

Epidemic intelligence service officers and field epidemiology training program in Korea.

Korea has adopted Epidemic Intelligence Service (EIS) officers through the Field Epidemiology Training Program (FETP) since 1999 for systematic control of emerging and re-emerging infectious diseases. Graduates of medical schools in Korea are selected and serve as public health doctors (PHDs) for their mandatory military service. The duration of service is 3 years and PHDs comprise general practitioners and specialists. Some PHDs are selected as EIS officers with 3 weeks basic FETP training and work for central and provincial public health authorities to conduct epidemiological investigations. The total number of EIS officers is 31 as of 2012. The Korea Centers for Disease Control and Prevention (KCDC) has 12 specialists, whereas specialists and each province has one or two EIS officers to administer local epidemiological investigations in 253 public health centers. The Korean EIS officers have successfully responded and prevented infectious diseases, but there is a unique limitation: the number of PHDs in Korea is decreasing and PHDs are not allowed to stay outside Korea, which makes it difficult to cope with overseas infectious diseases. Furthermore, after 3 years service, they quit and their experiences are not accumulated. KCDC has hired full-time EIS officers since 2012 to overcome this limitation.

Evaluation of the Effectiveness of Pandemic Influenza A(H1N1) 2009 Vaccine Based on an Outbreak Investigation During the 2010-2011 Season in Korean Military Camps.

OBJECTIVES: In December 2010, there was an outbreak of acute febrile respiratory disease in many Korean military camps that were not geographically related. A laboratory analysis confirmed a number of these cases to be infected by the pandemic influenza A(H1N1) 2009 (H1N1pdm09) virus. Because mass vaccination against H1N1pdm09 was implemented at the infected military camps eleven months ago, the outbreak areas in which both vaccinated and nonvaccinated individuals were well mixed, gave us an opportunity to evaluate the effectiveness of H1N1pdm09 vaccine through a retrospective cohort study design. METHODS: A self-administered questionnaire was distributed to the three military camps in which the outbreak occurred for case detection, determination of vaccination status, and characterization of other risk factors. The overall response rate was 86.8% (395/455). Case was defined as fever (≥38 °C) with cough or sore throat, influenza-like illness (ILI), and vaccination status verified by vaccination registry. Crude vaccine effectiveness (VE) was calculated as "1 - attack rate in vaccinated individuals/attack rate in nonvaccinated individuals", and adjusted VE was calculated as "1 - odds ratio" using logistic regression adjusted for potential confounding factor. A number of ILI definitions were used to test the robustness of the result. RESULTS: The attack rate of ILI was 12.8% in register-verified vaccinated individuals and 24.0% in nonvaccinated individuals. The crude VE was thus calculated to be 46.8% [95% confidence interval (CI): 14.5-66.9]. The adjusted VE rate was 46.8% (95% CI: -9.4 to 74.1). Various combinations of ILI symptoms also showed similar VE rates. CONCLUSION: We evaluated the effectiveness of H1N1pdm09 vaccine in the 2010-2011 season in an outbreak setting. Although the result was not sensitive to any analytical method used and ILI case definition, the magnitude of effectiveness was lower than estimated in the 2009-2010 season.