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1.
Frontiers in public health ; 10, 2022.
Article in English | EuropePMC | ID: covidwho-1989245

ABSTRACT

Background The incubation period of the coronavirus disease 2019 (COVID-19) is estimated to vary by demographic factors and the COVID-19 epidemic periods. Objective This study examined the incubation period of the wild type of SARS-CoV-2 infections by the different age groups, gender, and epidemic periods in South Korea. Methods We collected COVID-19 patient data from the Korean public health authorities and estimated the incubation period by fitting three different distributions, including log-normal, gamma, and Weibull distributions, after stratification by gender and age groups. To identify any temporal impact on the incubation period, we divided the study period into two different epidemic periods (Period-1: 19 January−19 April 2020 and Period-2: 20 April−16 October 2020), and assessed for any differences. Results We identified the log-normal as the best-fit model. The estimated median incubation period was 4.6 (95% CI: 3.9–4.9) days, and the 95th percentile was 11.7 (95% CI: 10.2–12.2) days. We found that the incubation period did not differ significantly between males and females (p = 0.42), age groups (p = 0.60), and the two different epidemic periods (p = 0.77). Conclusions The incubation period of wild type of SARS-CoV-2 infection during the COVID-19 pandemic 2020, in South Korea, does not likely differ by age group, gender and epidemic period.

3.
Medicine (Baltimore) ; 101(30): e29596, 2022 Jul 29.
Article in English | MEDLINE | ID: covidwho-1967937

ABSTRACT

The coronavirus disease 2019 (COVID-19) resulted in a marked decrease in the number of patient visits for acute myocardial infarction and delayed patient response and intervention in several countries. This study evaluated the effect of the COVID-19 pandemic on the number of patients, patient response time (pain-to-door), and intervention time (door-to-balloon) for patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI). Patients with STEMI or NSTEMI visiting a hospital in South Korea who underwent primary coronary intervention during the COVID-19 pandemic (January 29, 2020, to December 31, 2020) were compared with those in the equivalent period from 2018 to 2019. Patient response and intervention times were compared for the COVID-19 pandemic window (2020) and the equivalent period from 2018 to 2019. We observed no decrease in the number of patients with STEMI (P = .88) and NSTEMI (P = 1.00) during the COVID-19 pandemic compared to that in the previous years. Patient response times (STEMI: P = .39; NSTEMI: P = .59) during the overall COVID-19 pandemic period did not differ significantly. However, we identified a significant decrease in door-to-balloon time among patients with STEMI (14%; P < .01) during the early COVID-19 pandemic. We found that the number of patients with STEMI and NSTEMI was consistent during the COVID-19 pandemic and that no time delays in patient response and intervention occurred. However, the door-to-balloon time among patients with STEMI significantly reduced during the early COVID-19 pandemic, which could be attributed to decreased emergency care utilization during the early pandemic.


Subject(s)
COVID-19 , Myocardial Infarction , Non-ST Elevated Myocardial Infarction , Percutaneous Coronary Intervention , ST Elevation Myocardial Infarction , COVID-19/epidemiology , Humans , Myocardial Infarction/etiology , Myocardial Infarction/therapy , Non-ST Elevated Myocardial Infarction/etiology , Non-ST Elevated Myocardial Infarction/therapy , Pandemics , Percutaneous Coronary Intervention/adverse effects , ST Elevation Myocardial Infarction/etiology , ST Elevation Myocardial Infarction/therapy , Time Factors , Treatment Outcome
4.
One Health ; 15: 100425, 2022 Dec.
Article in English | MEDLINE | ID: covidwho-1966972

ABSTRACT

Based on exposure history and symptom onset of 22 Omicron BA.1 cases in South Korea from November to December 2021, we estimated mean incubation period of 3.5 days (95% CI: 2.5, 3.8), and then compared to that of 6.5 days (95% CI: 5.3, 7.7) for 64 cases during Delta variants' dominance in June 2021. For Omicron BA.1 variants, we found that 95% of symptomatic cases developed clinical conditions within 6.0 days (95% CI: 4.3, 6.6) after exposure. Thus, a shorter quarantine period may be considered based on symptoms, or similarly laboratory testing, when Omicron BA.1 variants are circulating.

6.
PLoS Comput Biol ; 18(6): e1010281, 2022 06.
Article in English | MEDLINE | ID: covidwho-1910467

ABSTRACT

In the context of infectious disease transmission, high heterogeneity in individual infectiousness indicates that a few index cases can generate large numbers of secondary cases, a phenomenon commonly known as superspreading. The potential of disease superspreading can be characterized by describing the distribution of secondary cases (of each seed case) as a negative binomial (NB) distribution with the dispersion parameter, k. Based on the feature of NB distribution, there must be a proportion of individuals with individual reproduction number of almost 0, which appears restricted and unrealistic. To overcome this limitation, we generalized the compound structure of a Poisson rate and included an additional parameter, and divided the reproduction number into independent and additive fixed and variable components. Then, the secondary cases followed a Delaporte distribution. We demonstrated that the Delaporte distribution was important for understanding the characteristics of disease transmission, which generated new insights distinct from the NB model. By using real-world dataset, the Delaporte distribution provides improvements in describing the distributions of COVID-19 and SARS cases compared to the NB distribution. The model selection yielded increasing statistical power with larger sample sizes as well as conservative type I error in detecting the improvement in fitting with the likelihood ratio (LR) test. Numerical simulation revealed that the control strategy-making process may benefit from monitoring the transmission characteristics under the Delaporte framework. Our findings highlighted that for the COVID-19 pandemic, population-wide interventions may control disease transmission on a general scale before recommending the high-risk-specific control strategies.


Subject(s)
COVID-19 , Communicable Diseases , COVID-19/epidemiology , Communicable Diseases/epidemiology , Humans , Likelihood Functions , Models, Statistical , Pandemics/prevention & control
7.
Viruses ; 14(5)2022 05 17.
Article in English | MEDLINE | ID: covidwho-1869811

ABSTRACT

Many countries have implemented public health and social measures (PHSMs) to control the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Although the PHSMs are targeted at SARS-CoV-2 transmission control, they directly or indirectly impact the epidemiology of different respiratory viral diseases. The purpose of this study was to investigate the collateral impact of PHSMs used during the coronavirus disease 2019 (COVID-19) pandemic on the epidemiology of other respiratory viruses, including influenza, parainfluenza, respiratory syncytial virus, rhinovirus, and adenovirus infections. We conducted a systematic review of the published literature on changes in the incidence of respiratory viral diseases and detection rates of the respiratory viruses during COVID-19 pandemic, lasting from 2020-2021, published between December 2019 and March 2022 in PubMed, Embase, and Cochrane Library databases. We identified an overall decrease of 23-94% in the incidence of respiratory viral diseases and a decrease of 0-98% in the detection of the viruses. Our study suggests that the PHSMs implemented during COVID-19 pandemic reduced the incidence of respiratory viral diseases and transmission of respiratory viruses. At the time of this study, and as governments relax PHSMs, public health authorities should prepare for a probable increase in the burden of respiratory viral diseases.


Subject(s)
COVID-19 , Respiratory Syncytial Virus, Human , Respiratory Tract Infections , Viruses , COVID-19/epidemiology , Humans , Pandemics , Public Health , Respiratory Tract Infections/epidemiology , SARS-CoV-2
9.
EuropePMC; 2022.
Preprint in English | EuropePMC | ID: ppcovidwho-331505

ABSTRACT

Introduction: Relative bradycardia(RB) is a relatively low heart rate response to rise in body temperature that occurs in several infectious diseases and can be an important clinical sign. In previous case reports, RB was presented in some patients with COVID-19. Objective and Methods: To investigate the correlation between temperature and heart rate, we retrospectively reviewed 249 febrile patients with documented COVID-19 patients. RB was defined as a rise in the heart rate (HR) from a basal HR of less than 10 beats/minute/°C rise in temperature. Results: In this study, the prevalence of RB in patients with COVID-19 was 60.6%. When the HR at peak temperatures for patients with COVID-19 were compared with reference valve (general temperature-heart rate response in infectious disease), our findings demonstrate a relatively lower heart rate at all peak temperatures recorded. Despite differences in HR response, there were not significant differences in clinical outcomes (pulmonary manifestation, ICU care, Death). Conclusion: Most patients with COVID-19 are associated with relative bradycardia, not related to clinical outcomes. RB in COVID-19 can be considered as the clinical features for differential diagnosis from other febrile conditions.

10.
Viruses ; 14(3)2022 03 04.
Article in English | MEDLINE | ID: covidwho-1732240

ABSTRACT

The omicron variant (B.1.1.529) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the predominant variant in South Korea from late January 2022. In this study, we aimed to report the early estimates of the serial interval distribution and reproduction number to quantify the transmissibility of the omicron variant in South Korea between 25 November 2021 and 31 December 2021. We analyzed 427 local omicron cases and reconstructed 73 transmission pairs. We used a maximum likelihood estimation to assess serial interval distribution from transmission pair data and reproduction numbers from 74 local cases in the first local outbreak. We estimated that the mean serial interval was 3.78 (standard deviation, 0.76) days, which was significantly shorter in child infectors (3.0 days) compared to adult infectors (5.0 days) (p < 0.01). We estimated the mean reproduction number was 1.72 (95% CrI, 1.60-1.85) for the omicron variant during the first local outbreak. Strict adherence to public health measures, particularly in children, should be in place to reduce the transmission risk of the highly transmissible omicron variant in the community.


Subject(s)
COVID-19 , SARS-CoV-2 , Adult , COVID-19/epidemiology , Child , Humans , Reproduction , Republic of Korea/epidemiology , SARS-CoV-2/genetics
11.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-320423

ABSTRACT

Background: After relaxing social distancing measures, South Korea experienced a resurgent second epidemic wave of coronavirus disease 2019 (COVID-19). In this study, we aimed to identify the transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and assess the impact of COVID-19 case finding and contact tracing in each epidemic wave. Methods: : We collected data on COVID-19 cases published by local public health authorities in South Korea and divided the study into two epidemic periods (19 January–19 April 2020 for the first epidemic wave and 20 April–11 August 2020 for the second epidemic wave). To identify changes in the transmissibility of SARS-CoV-2, the daily effective reproductive number ( R t ) was estimated using the illness onset of the cases. Furthermore, to identify the characteristics of each epidemic wave, frequencies of cluster types were measured, and age-specific transmission probability matrices and serial intervals were estimated. The proportion of asymptomatic cases and cases with unknown sources of infection were also estimated to assess the changes of infections identified as cases in each wave. Results: : In early May 2020, within 2-weeks of a relaxation in strict social distancing measures, R t increased rapidly from 0.2 to 1.8 within a week and was around 1 until early July 2020. In both epidemic waves, the most frequent cluster types were religious-related activities and transmissions among the same age were more common. Furthermore, children were rarely infectors or infectees, and the mean serial intervals were similar (~3 days) in both waves. The proportion of asymptomatic cases at presentation increased from 22% (in the first wave) to 27% (in the second wave), while the cases with unknown sources of infection were similar in both waves (22% and 24%, respectively). Conclusions: : Our study shows that relaxing social distancing measures was associated with increased SARS-CoV-2 transmission despite rigorous case findings in South Korea. Along with social distancing measures, the enhanced contact tracing including asymptomatic cases could be an efficient approach to control further epidemic waves.

12.
Prev Med Rep ; 26: 101728, 2022 Apr.
Article in English | MEDLINE | ID: covidwho-1671043

ABSTRACT

Social distancing measures including school closure and the cancelation of sports activity were enforced during the early phase of the coronavirus disease 2019 (COVID-19) pandemic to reduce the spread of severe acute respiratory syndrome coronavirus 2 in South Korea. To assess the impact of the COVID-19 pandemic on the nationwide burden of musculoskeletal injury in 2020, we analyzed data on the number of patient visits for ankle sprain in South Korea. We collected national reimbursement data on the number of patient visits for ankle sprain between August 2010 and July 2020. To quantify the impact of the COVID-19 pandemic on the number of reductions in patient visits for ankle sprain, we developed a regression model adjusting for the annual cycle of the patient visit during 2016/17-2018/19. During the COVID-19 pandemic in South Korea, the overall number of patient visits for ankle sprain dropped by 7.9%. The number of patient visits for ankle sprain substantially reduced by 23.4% among school-aged children (6-19 years) during the COVID-19 pandemic in South Korea. Our findings suggest that the social distancing measure has had a positive impact on reducing the burden of medical usages for ankle sprain.

13.
Open Forum Infect Dis ; 8(11): ofab432, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1584166

ABSTRACT

[This corrects the article DOI: 10.1093/ofid/ofab350.].

14.
Emerg Infect Dis ; 28(2): 407-410, 2022 02.
Article in English | MEDLINE | ID: covidwho-1575455

ABSTRACT

We estimated mean serial interval and superspreading potential for the Delta variant of severe acute respiratory syndrome coronavirus 2 in South Korea. Intervals were similar for the first (3.7 days) and second (3.5 days) study periods. Risk for superspreading events was also similar; 23% and 25% of cases, respectively, seeded 80% of transmissions.


Subject(s)
COVID-19 , SARS-CoV-2 , Humans , Republic of Korea/epidemiology
15.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-295872

ABSTRACT

We estimated mean serial interval and superspreading potential for the predominant Delta variant of SARS-CoV-2. Mean serial intervals were similar with 3.7 and 3.5 days during early and latter periods, respectively. Furthermore, the risk of superspreading events was similar with 23% and 25% of cases seeded 80% of all transmissions.

16.
2021.
Preprint in English | Other preprints | ID: ppcovidwho-295871

ABSTRACT

Background The coronavirus disease 2019 (COVID-19) resulted in a marked decrease in the number of patient visits for acute myocardial infarction (AMI) and delayed patient response and intervention in several countries. This study evaluated the effect of the COVID-19 pandemic on the number of patients, patient response time (pain-to-door), and intervention time (door-to-balloon) for patients with ST-segment elevation myocardial infarction (STEMI) and non-ST-segment elevation myocardial infarction (NSTEMI). Methods Patients with STEMI or NSTEMI visiting a hospital in South Korea who underwent primary coronary intervention during the COVID-19 pandemic (January 29, 2020, to December 31, 2020) were compared with those in the equivalent period in 2018 to 2019. Patient response and intervention times were compared for the COVID-19 pandemic window (2020) and the equivalent period in 2018 to 2019. Results We observed no decrease in the number of patients with STEMI ( P =0.50) and NSTEMI ( P =0.94) during the COVID-19 pandemic compared to that in the previous years. Patient response times (STEMI: P =0.34;NSTEMI: P =0.89) during the overall COVID-19 pandemic period did not differ significantly. However, we identified a significant decrease in time to intervention among patients with STEMI (14%;p<0.01) during the early COVID-19 pandemic. Conclusions We found that the number of patient with STEMI and NSTEMI was consistent during the COVID-19 pandemic and that no time delays in patient response and intervention occurred. However, the door-to-balloon time among patients with STEMI significantly reduced during the early COVID-19 pandemic, which could be attributed to reduced emergency care utilization during the early pandemic.

17.
EuropePMC; 2021.
Preprint in English | EuropePMC | ID: ppcovidwho-294995

ABSTRACT

Background: The delta variant of SARS-CoV-2 is now the predominant variant worldwide. However, its transmission dynamics remain unclear. Methods We analyzed all case patients in local clusters and temporal patterns of viral shedding using contact tracing data from 405 cases associated with the delta variant of SARS-CoV-2 between 22 June and 31 July 2021 in Daejeon, South Korea. Results Overall, half of the cases were aged under 19 years, and 20% were asymptomatic at the time of epidemiological investigation. We estimated the mean serial interval as 3.26 days (95% credible interval 2.92, 3.60), and 12% of the transmission occurred before symptom onset of the infector. We identified six clustered outbreaks, and all were associated with indoor facilities. In 23 household contacts, the secondary attack rate was 63% (52/82). We estimated that 15% (95% confidence interval, 13–18%) of cases seeded 80% of all local transmission. Analysis of the nasopharyngeal swab samples identified virus shedding from asymptomatic patients, and the highest viral load was observed two days after symptom onset. The temporal pattern of viral shedding did not differ between children and adults ( P  = 0.48). Conclusions Our findings suggest that the delta variant is highly transmissible in indoor settings and households. Rapid contact tracing, isolation of the asymptomatic contacts, and strict adherence to public health measures are needed to mitigate the community transmission of the delta variant.

18.
Open Forum Infect Dis ; 8(11): ofab432, 2021 Nov.
Article in English | MEDLINE | ID: covidwho-1550575

ABSTRACT

[This corrects the article DOI: 10.1093/ofid/ofab350.].

19.
J Infect Dis ; 225(5): 793-799, 2022 03 02.
Article in English | MEDLINE | ID: covidwho-1550555

ABSTRACT

BACKGROUND: The Delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was the predominant variant worldwide at the time of this study. However, its transmission dynamics were unclear. METHODS: We analyzed 405 local cases infected with the Delta variant of SARS-CoV-2 and temporal patterns of viral shedding identified between 22 June and 31 July 2021 in Daejeon, South Korea. RESULTS: Overall, 20% were presymptomatic at the time of epidemiological investigation. We identified 6 clustered outbreaks, and all were associated with indoor facilities. In 23 household contacts, the secondary attack rate was 63%. We estimated the mean serial interval as 3.26 days (95% credible interval, 2.92-3.60), and 15% (95% confidence interval, 13%-18%) of cases seeded 80% of all local transmission. Analysis of the nasopharyngeal swab samples identified virus shedding from the presymptomatic cases and the highest viral load was observed 2 days after symptom onset. CONCLUSIONS: Our findings suggest that the Delta variant is highly transmissible in indoor settings and households. Rapid contact tracing, isolation of the asymptomatic contacts, strict adherence to public health measures, and increased uptake of coronavirus disease 2019 (COVID-19) vaccination, including booster doses, are needed to reduce community transmission of the Delta variant.


Subject(s)
COVID-19/epidemiology , COVID-19/transmission , Communicable Disease Control/methods , SARS-CoV-2 , Adolescent , Adult , Aged , COVID-19/prevention & control , Child , Child, Preschool , Contact Tracing , Disease Outbreaks , Female , Humans , Incidence , Infant , Infant, Newborn , Male , Middle Aged , Republic of Korea/epidemiology , Reverse Transcriptase Polymerase Chain Reaction , SARS-CoV-2/genetics , Virus Shedding
20.
Sci Rep ; 11(1): 18938, 2021 09 23.
Article in English | MEDLINE | ID: covidwho-1437693

ABSTRACT

Coronavirus disease (COVID-19) has been spreading all over the world; however, its incidence and case-fatality ratio differ greatly between countries and between continents. We investigated factors associated with international variation in COVID-19 incidence and case-fatality ratio (CFR) across 107 northern hemisphere countries, using publicly available COVID-19 outcome data as of 14 September 2020. We included country-specific geographic, demographic, socio-economic features, global health security index (GHSI), healthcare capacity, and major health behavior indexes in multivariate models to explain this variation. Multiple linear regression highlighted that incidence was associated with ethnic region (p < 0.05), global health security index 4 (GHSI4) (beta coefficient [ß] 0.50, 95% Confidence Interval [CI] 0.14-0.87), population density (ß 0.35, 95% CI 0.10-0.60), and water safety level (ß 0.51, 95% CI 0.19-0.84). The CFR was associated with ethnic region (p < 0.05), GHSI4 (ß 0.53, 95% CI 0.14-0.92), proportion of population over 65 (ß 0.71, 95% CI 0.19-1.24), international tourism receipt level (ß - 0.23, 95% CI - 0.43 to - 0.03), and the number of physicians (ß - 0.37, 95% CI - 0.69 to - 0.06). Ethnic region was the most influential factor for both COVID-19 incidence (partial [Formula: see text] = 0.545) and CFR (partial [Formula: see text] = 0.372), even after adjusting for various confounding factors.


Subject(s)
COVID-19/epidemiology , COVID-19/mortality , Mortality/trends , Global Health , Humans , Incidence , Population Density , Risk Factors , SARS-CoV-2/pathogenicity
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