Corrigendum to "Middle East Respiratory Syndrome Coronavirus Outbreak in the Republic of Korea, 2015" [Volume 6, Issue 4, August 2015, 269-278].
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SUBMITTER: Korea Centers for Disease Control and Prevention
PROVIDER: S-EPMC4850385 | biostudies-literature | 2016 Apr
REPOSITORIES: biostudies-literature
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Corrigendum to "Middle East Respiratory Syndrome Coronavirus Outbreak in the Republic of Korea, 2015" [Volume 6, Issue 4, August 2015, 269-278].
Osong public health and research perspectives 20160410 2
[This corrects the article DOI: 10.1016/j.phrp.2015.08.006.]. ...[more]
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Project description:BACKGROUND:Emerging respiratory infections represent a significant public health threat. Because of their novelty, there are limited measures available to control their early spread. Learning from past outbreaks is important for future preparation. The Middle Eastern Respiratory Syndrome CoronaVirus (MERS-CoV ) 2015 outbreak in the Republic of Korea (ROK) provides one such opportunity. OBJECTIVES:We demonstrated through quantitative methodologies how to estimate MERS-CoV's transmissibility and identified the effective countermeasures that stopped its spread. METHODS:Using the outbreak data, statistical methods were employed to estimate the basic reproductive number R0 , the average number of secondary cases produced by a typical primary case during its entire infectious period in a fully susceptible population. A transmission dynamics model was also proposed to estimate R0 and to identify the most effective countermeasures. The consistency between results will provide cross-validation of the approaches. RESULTS:R0 ranged from 2.5 with 95% confidence interval (CI): [1.7, 3.1] (using the sequential Bayesian method) to 7.2 with 95% CI: [5.3, 9.4] (using the Nowcasting method). Estimates from transmission model were higher but overlapped with these. Personal protection and rapid confirmation of cases were identified as the most important countermeasures. CONCLUSIONS:Our estimates were in agreement with others from the ROK outbreak, albeit significantly higher than estimates based on other small outbreaks and sporadic cases of MERS-CoV. The large-scale outbreak in the ROK was jointly due to the high transmissibility in the healthcare-associated setting and the Korean culture-associated contact behaviour. Limiting such behaviour by rapidly identifying and isolating cases and avoiding high-risk contacts effectively stopped further transmission.
| S-EPMC5598245 | biostudies-literature
Project description:To investigate the heterogeneous transmission patterns of Middle East respiratory syndrome (MERS) in the Republic of Korea, with a particular focus on epidemiological characteristics of superspreaders.Retrospective epidemiological analysis.Multiple healthcare facilities of secondary and tertiary care centres in an urban setting.A total of 185 laboratory-confirmed cases with partially known dates of illness onset and most likely sources of infection.Superspreaders were identified using the transmission tree. The reproduction number, that is, the average number of secondary cases produced by a single primary case, was estimated as a function of time and according to different types of hosts.A total of five superspreaders were identified. The reproduction number throughout the course of the outbreak was estimated at 1.0 due to reconstruction of the transmission tree, while the variance of secondary cases generated by a primary case was 52.1. All of the superspreaders involved in this outbreak appeared to have generated a substantial number of contacts in multiple healthcare facilities (association: p<0.01), generating on average 4.0 (0.0-8.6) and 28.6 (0.0-63.9) secondary cases among patients who visited multiple healthcare facilities and others. The time-dependent reproduction numbers declined substantially below the value of 1 on and after 13 June 2015.Superspreaders who visited multiple facilities drove the epidemic by generating a disproportionate number of secondary cases. Our findings underscore the need to limit the contacts in healthcare settings. Contact tracing efforts could assist early laboratory testing and diagnosis of suspected cases.
| S-EPMC4769415 | biostudies-other
Project description:BackgroundEpidemiologic parameters are important in planning infection control policies during the outbreak of emerging infections. Korea experienced an outbreak of Middle East Respiratory Syndrome coronavirus (MERS-CoV) infection in 2015, which was characterized by superspreading events in healthcare settings. We aimed to estimate the epidemiologic parameters over time during the outbreak to assess the effectiveness of countermeasures.Materials and methodsPublicly available data pertaining to the MERS outbreak in Korea were collected. We estimated the incubation periods of 162 cases whose sources of exposure were identified and the temporal trend was evaluated. Factors influencing incubation duration were analyzed. The generational reproduction number (Rg ) and case reproduction number (R(c) ) were estimated over time.ResultsThe estimated median incubation period was 7.4 days (95% CI, 6.9-8.0). Median incubation periods tended to be longer over time as the disease generation progressed: 6.16 days (95% CI, 5.38-6.97), 7.68 days (95% CI, 7.04-8.44), and 7.95 days (95% CI, 6.25-9.88) in the first, second, and third generations, respectively. The number of days of illness in the source cases at the time of exposure inversely correlated with the incubation periods in the receiving cases (HR 0.91 [95% CI, 0.84-0.99] per one illness day increase; P=0.026). This relationship was consistent (HR 0.83 [95% CI, 0.74-0.93] per one illness day increase) in the multivariable analysis incorporating clinical characteristics, the order of generation, and a link to superspreaders. Because the third generation cases were exposed to their source cases in the early stage (median one day) compared to the second generation cases (median 6 days), the temporal trend of incubation periods appears to be influenced by early isolation of symptomatic cases and reduction of potential exposure to source cases in the later stage. Rg declined rapidly from 28 to 0.23 in two generations. R(c) dropped below the epidemic threshold at one on May 31, 2015, which approximately coincided with the initiation of the stringent countermeasures.ConclusionsDespite the initial delay, the stringent countermeasures targeted towards second generation cases appeared to effectively contain the MERS outbreak in Korea as suggested by the decline of R(c) shortly after implementation. Except for superspreading events, the transmission potential for MERS-CoV seems to be low. Further research should be focused on characterizing superspreaders in comparison to non-transmitting cases with regard to environmental, behavioral, and virologic and host genetic factors in order to better prepare for future outbreaks of MERS-CoV.
| S-EPMC4945720 | biostudies-literature
Project description:During the 2015 Middle East respiratory syndrome coronavirus outbreak in South Korea, we sequenced full viral genomes of strains isolated from 4 patients early and late during infection. Patients represented at least 4 generations of transmission. We found no evidence of changes in the evolutionary rate and no reason to suspect adaptive changes in viral proteins.
| S-EPMC4734539 | biostudies-literature
Project description:Background. Since the emergence of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in 2012, more than 1,300 laboratory confirmed cases of MERS-CoV infections have been reported in Asia, North Africa, and Europe by July 2015. The recent MERS-CoV nosocomial outbreak in South Korea quickly became the second largest such outbreak with 186 total cases and 36 deaths in a little more than one month, second only to Saudi Arabia in country-specific number of reported cases. Methods. We use a simple mathematical model, the Richards model, to trace the temporal course of the South Korea MERS-CoV outbreak. We pinpoint its outbreak turning point and its transmissibility via basic reproduction number R 0 in order to ascertain the occurrence of this nosocomial outbreak and how it was quickly brought under control. Results. The estimated outbreak turning point of ti = 23.3 days (95% CI [22.6-24.0]), or 23-24 days after the onset date of the index case on May 11, pinpoints June 3-4 as the time of the turning point or the peak incidence for this outbreak by onset date. R 0 is estimated to range between 7.0 and 19.3. Discussion and Conclusion. The turning point of the South Korea MERS-CoV outbreak occurred around May 27-29, when control measures were quickly implemented after laboratory confirmation of the first cluster of nosocomial infections by the index patient. Furthermore, transmissibility of MERS-CoV in the South Korea outbreak was significantly higher than those reported from past MERS-CoV outbreaks in the Middle East, which is attributable to the nosocomial nature of this outbreak. Our estimate of R 0 for the South Korea MERS-CoV nosocomial outbreak further highlights the importance and the risk involved in cluster infections and superspreading events in crowded settings such as hospitals. Similar to the 2003 SARS epidemic, outbreaks of infectious diseases with low community transmissibility like MERS-CoV could still occur initially with large clusters of nosocomial infections, but can be quickly and effectively controlled with timely intervention measures.
| S-EPMC4690341 | biostudies-literature
Project description:South Korea was free of the Middle East Respiratory Syndrome (MERS) until 2015. The MERS outbreak in South Korea during 2015 was the largest outbreak of the Coronavirus outside the Middle East. The major characteristic of this outbreak is inter- or intra-hospital transmission. This recent MERS outbreak in South Korea is examined and assessed in this paper. The main objectives of the study is to characterize the pattern of the MERS outbreak in South Korea based on a basic reproductive ratio, the probability of ultimate extinction of the disease, and the spatio-temporal proximity of occurrence between patients. The survival function method and stochastic branching process model are adapted to calculate the basic reproductive ratio and the probability of ultimate extinction of the disease. We further investigate the occurrence pattern of the outbreak using a spatio-temporal autocorrelation function.
| S-EPMC6595052 | biostudies-literature
Project description:PurposeIn May 2015, South Korea experienced an epidemic of Middle East respiratory syndrome (MERS). This study investigated the impacts of MERS epidemic on emergency care utilization and mortality in South Korea.Materials and methodsA natural experimental study was conducted using healthcare utilization and mortality data of the entire Korean population. The number of monthly emergency room (ER) visits was investigated to identify changes in emergency care utilization during the MERS epidemic; these trends were also examined according to patients' demographic factors, disease severity, and region. Deaths within 7 days after visiting an ER were analyzed to evaluate the impact of the reduction in ER visits on mortality.ResultsThe number of ER visits during the peak of the MERS epidemic (June 2015) decreased by 33.1% compared to the average figures from June 2014 and June 2016. The decrease was observed in all age, sex, and income groups, and was more pronounced for low-acuity diseases (acute otitis media: 53.0%; upper respiratory infections: 45.2%) than for high-acuity diseases (myocardial infarctions: 14.0%; ischemic stroke: 16.6%). No substantial changes were detected for the highest-acuity diseases, with increases of 3.5% for cardiac arrest and 2.4% for hemorrhagic stroke. The number of deaths within 7 days of an ER visit did not change significantly.ConclusionDuring the MERS epidemic, the number of ER visits decreased in all age, sex, and socioeconomic groups, and decreased most sharply for low-acuity diseases. Nonetheless, there was no significant change in deaths after emergency care.
| S-EPMC6660446 | biostudies-literature
Project description:Nosocomial transmission is an important characteristic of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) infection. Risk factors for transmission of MERS-CoV in healthcare settings are not well defined. During the Korean outbreak in 2015, 186 patients had laboratory-confirmed MERS-CoV infection. Those suspected as a source of viral transmission were categorized into the spreader groups (super-spreader [n = 5] and usual-spreader [n = 10]) and compared to the non-spreader group (n = 171). Body temperature of ≥ 38.5°C (adjusted odds ratio [aOR], 5.54; 95% confidence interval [CI], 1.38-22.30; P = 0.016), pulmonary infiltration of ≥ 3 lung zones (aOR, 7.33; 95% CI, 1.93-27.79; P = 0.003), and a more nonisolated in-hospital days (aOR, 1.32 per 1 day; 95% CI, 1.09-1.60; P = 0.004) were significant risk factors in the spreader group. There was no different clinical factor between super-spreaders and usual-spreaders. Nonisolated in-hospital days was the only factor which tended to be higher in super-spreaders than usual-spreaders (Mean, 6.6 vs. 2.9 days; P = 0.061). Early active quarantine might help reducing the size of an outbreak.
| S-EPMC5383605 | biostudies-literature
Project description:We conducted a retrospective study of Middle East respiratory syndrome coronavirus (MERS-CoV) viral load kinetics using data from patients hospitalised with MERS-CoV infection between 19 May and 20 August, 2015. Viral load trajectories were considered over the hospitalisation period using 1,714 viral load results measured in serial respiratory specimens of 185 patients. The viral load levels were significantly higher among non-survivors than among survivors (p=0.003). Healthcare workers (p = 0.001) and non-spreaders (p <0.001) had significantly lower viral loads. Viral RNA was present on the day of symptom onset and peaked 4-10 days after symptom onset.
| S-EPMC7454697 | biostudies-literature
Project description:An outbreak of the Middle East respiratory syndrome (MERS), comprising 185 cases linked to healthcare facilities, occurred in the Republic of Korea from May to July 2015. Owing to the nosocomial nature of the outbreak, it is particularly important to gain a better understanding of the epidemiological determinants characterizing the risk of MERS death in order to predict the heterogeneous risk of death in medical settings.We have devised a novel statistical model that identifies the risk of MERS death during the outbreak in real time. While accounting for the time delay from illness onset to death, risk factors for death were identified using a linear predictor tied to a logit model. We employ this approach to (1) quantify the risks of death and (2) characterize the temporal evolution of the case fatality ratio (CFR) as case ascertainment greatly improved during the course of the outbreak.Senior persons aged 60 years or over were found to be 9.3 times (95% confidence interval (CI), 5.3-16.9) more likely to die compared to younger MERS cases. Patients under treatment were at a 7.8-fold (95% CI, 4.0-16.7) significantly higher risk of death compared to other MERS cases. The CFR among patients aged 60 years or older under treatment was estimated at 48.2% (95% CI, 35.2-61.3) as of July 31, 2015, while the CFR among other cases was estimated to lie below 15%. From June 6, 2015, onwards, the CFR declined 0.3-fold (95% CI, 0.1-1.1) compared to the earlier epidemic period, which may perhaps reflect enhanced case ascertainment following major contact tracing efforts.The risk of MERS death was significantly associated with older age as well as treatment for underlying diseases after explicitly adjusting for the delay between illness onset and death. Because MERS outbreaks are greatly amplified in the healthcare setting, enhanced infection control practices in medical facilities should strive to shield risk groups from MERS exposure.
| S-EPMC4588253 | biostudies-literature