Application of Testing-TracingTreatment Strategy in Response to the COVID-19 Outbreak in Seoul, Korea

Background@#Following the coronavirus disease 2019 (COVID-19) outbreak in Wuhan, China, a total of 637 patients had been diagnosed with the disease in Seoul as of May 2, 2020. Our study aimed to describe the impact of the 3T strategies (preemptive testing, prompt tracing and proper treatment) on the epidemiological characteristics of COVID-19 in Seoul. @*Methods@#The descriptive and explanatory analysis was carried out on critical indicators such as epidemiological characteristics and key duration of patient status change from January 24 to May 2 in Seoul before and after preemptive testing for patients under investigation associated with COVID-19 clusters. @*Results@#Preemptive testing increased the positive test rate (3.9% to 4.2%), an asymptomatic case at diagnosis (16.9% to 30.6%), and reduced the time from symptom onset to quarantine (4.0 to 3.0 days). Prompt tracing decreased unknown sources of infection (6.9% to 2.8%), the mean number of contacts (32.2 to 23.6), and the time-varying reproduction number R(t) (1.3 to 0.6). With proper treatment, only 2 cases of mortality occurred, resulting in a fatality rate of just 0.3%. @*Conclusion@#In the first wave of the COVID-19 pandemic lasting 100 days, the effect of the 3T strategies flattened the curve and decreased the time during which infected individuals were contagious, thereby lowering the R(t) below 1 in Seoul.

Campylobacter jejuni Foodborne Infection Associated with Cross-contamination: Outbreak in Seoul in 2017

BACKGROUND@#In July 2017, there was an outbreak of Campylobacter jejuni infection in three auxiliary police squads in Seoul, Korea. An epidemiological investigation was conducted to identify the cause and source of the illness.@*MATERIALS AND METHODS@#A retrospective cohort study of all members of the three auxiliary police squads was conducted. Self-administered questionnaires were distributed to all members of the three squads and the food handlers. Rectal swabs were collected from symptomatic police and food handlers.@*RESULTS@#The overall attack rate was 20.4%, and the epidemic curve indicated a point source type outbreak. Of the 257 auxiliary policemen who consumed the incriminated lunch, 55 met the case definition. Of 36 rectal swabs, 10 were positive for C. jejuni and had the same pulsed-field gel electrophoresis pattern. The major symptoms were loose stool (100%) and abdominal pain (59.3%); the median incubation period was 69 hours. In the univariate epidemiological analysis, watermelon (relative risk [RR], 5.75; 95% confidence interval [CI], 2.14–15.43), half-cut chicken soup (RR, 3.96; 95% CI, 1.49–10.54), steamed rice with millet (RR, 2.73; 95% CI, 1.29–5.77), and radish kimchi (RR, 2.57; 95% CI, 1.45–4.55) were positively associated with the illness. Inspection of the food service facility found that the drainpipe under the meat cleaning sink did not work.@*CONCLUSION@#This outbreak could have been caused by cross-contamination with C. jejuni from raw chicken via environmental sources.

Cost-Effectiveness of Voluntary HIV Testing Strategies in a Very Low-Prevalence Country, the Republic of Korea

BACKGROUND: The Republic of Korea has a very low prevalence of human immunodeficiency virus (HIV) infection, but the number of new HIV diagnoses has steadily risen, strongly indicating a large number of undetected HIV infections. Thus, it is important for Korean public health authorities to adopt and encourage cost-effective HIV detection tools, such as rapid HIV screening tests. In this study, we aimed to evaluate the cost-effectiveness of enzyme-linked immunosorbent assays (ELISA) and rapid tests in a public health center (PHC) setting. METHODS: We developed a decision analytic model to assess the per-examinee cost and the cost-effectiveness of identifying HIV patients in a PHC setting using two HIV testing strategies: conventional HIV screening by ELISA versus rapid HIV testing. Analysis was performed in two scenarios: HIV testing in an average-risk population and in a high-risk population. RESULTS: Compared to the ELISA, the rapid test was cost-saving and cost-effective. The per-examinee cost was USD 1.61 with rapid testing versus USD 3.38 with ELISA in an average-risk population, and USD 4.77 with rapid testing versus USD 7.62 with ELISA in a high-risk population. The cost of identifying a previously undiagnosed HIV case was USD 26,974 with rapid testing versus USD 42,237 with ELISA in an average-risk population, and USD 153 with rapid testing versus USD 183 with ELISA in a high-risk population. CONCLUSION: Rapid testing would be more cost-effective than using conventional ELISA testing for identifying previously undiagnosed HIV-infected cases in Korea, a country with extremely low HIV prevalence.

Factors Contributing to Missed Visits for Medical Care among Human Immunodeficiency Virus-Infected Adults in Seoul, Korea

BACKGROUND: It is important that patients with human immunodeficiency virus (HIV) remain under medical care to improve their health and to reduce the potential for HIV transmission. We explored factors associated with missed visits for HIV medical care according to age group. METHODS: Data were derived from a city-wide, cross-sectional survey of 812 HIV-infected adults in Seoul. Multiple logistic analyses were used to explore predictors of missed visits. RESULTS: Of the 775 subjects, 99.3% were treated with antiretroviral therapy (ART) and 12.5% had missed a scheduled appointment for HIV medical care during the past 12 months. Compared with the group aged ≥ 50 years, the 20–34-years and 35–49-years groups were strongly associated with missed visits (adjusted odds ratio [aOR], 5.0 and 2.2, respectively). When divided by age group, lower education level (aOR, 3.0) in subjects aged 20–34 years, low income (aOR, 3.5), National Medical Aid beneficiary (aOR, 0.3), and treatment interruption due to side effects of ART (aOR, 3.4) in subjects aged 35–49 years, and National Medical Aid beneficiary (aOR, 7.1) in subjects aged ≥ 50 years were associated with missed visits. CONCLUSION: In conclusion, younger age was a strong predictor of missed visits for HIV medical care. However, the risk factors differed according to age group, and the strongest predictor in each age group was related to socioeconomic status.

Implementing Expanded Rapid Human Immunodeficiency Virus Testing in Public Health Centers in Seoul, 2015

In 2015, rapid human immunodeficiency virus (HIV) testing was implemented in all 25 public health centers in Seoul. During March and December 2015, 20,987 rapid HIV tests were performed, of which 116 (0.5%) were positive. Compared to those of the period before application of the rapid HIV test in place of conventional enzyme immunoassay method, the number of HIV tests performed and the number of positive results increased by sevenfold and twofold, respectively. In conclusion, expansion of the provision of rapid HIV tests in public health centers increased the number of voluntary HIV tests.

Implementing Expanded Rapid Human Immunodeficiency Virus Testing in Public Health Centers in Seoul, 2015

In 2015, rapid human immunodeficiency virus (HIV) testing was implemented in all 25 public health centers in Seoul. During March and December 2015, 20,987 rapid HIV tests were performed, of which 116 (0.5%) were positive. Compared to those of the period before application of the rapid HIV test in place of conventional enzyme immunoassay method, the number of HIV tests performed and the number of positive results increased by sevenfold and twofold, respectively. In conclusion, expansion of the provision of rapid HIV tests in public health centers increased the number of voluntary HIV tests.

An Outbreak of Scombroid Fish Poisoning Associated with Consumption of Yellowtail Fish in Seoul, Korea

BACKGROUND: In November 2016, an outbreak of scombroid fish poisoning occurred among elementary school students in Seoul, Korea. An epidemiological investigation was conducted to identify the cause and source of the illness. METHODS: A case-control study was conducted among school members who had eaten lunch in the school. The histamine level in the suspect food item (yellowtail steak) was measured. RESULTS: Fifty-five (5.4%) of 1,017 school members who consumed fish for lunch fell ill. The principal symptoms were flushing (100%) and headache (72.7%); the median incubation period was 40 minutes. All had consumed yellowtail steak (odds ratio, 9.24; 95% confidence interval, 1.22–69.91). Leftover steak had an elevated histamine level (293 mg/kg), higher than the allowed 200 mg/kg. CONCLUSION: An outbreak of scombroid fish poisoning was confirmed; this is the first such report in Korea. Detailed food safety guidelines must be established.

Effectiveness of Varicella Vaccination Program in Preventing Laboratory-Confirmed Cases in Children in Seoul, Korea

A universal one-dose varicella vaccination program was introduced in 2005 in Republic of Korea. However, the incidence of varicella in Korea has tripled over the last decade. We conducted a community based 1:1 matched case-control study to assess the effectiveness of one MAV strain-based vaccine and three Oka strain-based vaccines licensed for use in Korea. All cases were children in Seoul, Korea with varicella who were reported to the National Notifiable Disease Surveillance System in Seoul during 2013. The controls were age-matched children with mumps or scarlet fever but no history of varicella. We included 537 cases and 537 controls. The overall effectiveness of one dose of varicella vaccination was 13% (95% confidence interval [CI], −17.3–35.6). Of the four licensed varicella vaccines, only one was highly effective (88.9%; 95% CI, 52.1–97.4). The vaccine effectiveness for the other vaccines were 71.4% (95% CI, −37.5–94.1), −5% (95% CI, −61.9–31.9), and −100% (95% CI, −700–50.0). The overall effectiveness of vaccination was 75.8% (95% CI, 22.8–92.4) in the first year after vaccination and decreased thereafter; the effectiveness became −7.2% (95% CI, −130.9–59.2) in the fourth year after vaccination. Further studies are warranted to investigate reduced effectiveness of varicella vaccines in Korea.

Implementing the Use of Rapid HIV Tests in Public Health Centers in Seoul: Results of a Pilot Project, 2014

To determine whether rapid HIV tests in public health centers might encourage voluntary HIV testing, a pilot project was conducted in four selected public health centers in Seoul, 2014. During the period April 10 to November 28 of pilot project, 3,356 rapid tests were performed, and 38 were confirmed as positive. The monthly average numbers of voluntary HIV tests and HIV-positive cases were up to nine-fold and six-fold larger, respectively, than those of the period before application of the rapid HIV test. Among 2,051 examinees that completed questionnaires, 90.3% were satisfied. In conclusion, the use of rapid HIV tests in public health centers promoted voluntary HIV testing and was satisfactory for examinees.

Patients Presenting with Advanced Human Immunodeficiency Virus Disease: Epidemiological Features by Age Group

We explored factors influencing presentation with advanced human immunodeficiency virus (HIV) disease by age group. Data were derived from a city-wide cross-sectional survey of 759 HIV-infected adults living in Seoul, Korea. The significance of each observed factor was assessed via multivariate logistic regression. Of subjects aged 20-34 years, lower educational level had a positive influence on presentation with advanced HIV disease (adjusted odds ratio [aOR], 2.43; 95% confidence interval [CI], 1.36-4.34); those recently diagnosed with HIV were more likely to be presented with advanced HIV disease (aOR, 3.17; 95% CI, 0.99-10.2). Of the subjects aged 35-49 years, those w ith advanced HIV disease were more likely to have been diagnosed during health check-ups (aOR, 2.91; 95% CI, 1.15-7.32) or via clinical manifestations (aOR, 3.61; 95% CI, 1.39-9.36). Of the subjects aged > or = 50 years, presentation with advanced HIV disease was significantly more common in older subjects (aOR per increment of 5 years, 2.06; 95% CI, 1.32-3.23) and less common among individuals diagnosed with HIV in 2000-2006 (aOR, 0.18; 95% CI, 0.04-0.83). In conclusion, a lower educational level in younger subjects and more advanced age in older subjects positively influence the presentation of advanced HIV disease.

Patients Presenting with Advanced Human Immunodeficiency Virus Disease: Epidemiological Features by Age Group

We explored factors influencing presentation with advanced human immunodeficiency virus (HIV) disease by age group. Data were derived from a city-wide cross-sectional survey of 759 HIV-infected adults living in Seoul, Korea. The significance of each observed factor was assessed via multivariate logistic regression. Of subjects aged 20-34 years, lower educational level had a positive influence on presentation with advanced HIV disease (adjusted odds ratio [aOR], 2.43; 95% confidence interval [CI], 1.36-4.34); those recently diagnosed with HIV were more likely to be presented with advanced HIV disease (aOR, 3.17; 95% CI, 0.99-10.2). Of the subjects aged 35-49 years, those w ith advanced HIV disease were more likely to have been diagnosed during health check-ups (aOR, 2.91; 95% CI, 1.15-7.32) or via clinical manifestations (aOR, 3.61; 95% CI, 1.39-9.36). Of the subjects aged > or = 50 years, presentation with advanced HIV disease was significantly more common in older subjects (aOR per increment of 5 years, 2.06; 95% CI, 1.32-3.23) and less common among individuals diagnosed with HIV in 2000-2006 (aOR, 0.18; 95% CI, 0.04-0.83). In conclusion, a lower educational level in younger subjects and more advanced age in older subjects positively influence the presentation of advanced HIV disease.