Analyses of Confirmed COVID-19 Cases Among Korean Military Personnel After Mass Vaccination

BackgroundThe military was one of the first groups in Korea to complete mass vaccination against the coronavirus disease 2019 (COVID-19) due to their high vulnerability to COVID-19. To confirm the effect of mass vaccination, this study analyzed the patterns of confirmed cases within Korean military units.MethodsFrom August 1 to September 15, 2021, all epidemiological data regarding confirmed COVID-19 cases in military units were reviewed. The number of confirmed cases in the units that were believed to have achieved herd immunity (i.e., ≥ 70% vaccination) was compared with the number of cases in the units that were not believed to have reached herd immunity (< 70% vaccination). Additionally, trends in the incidence rates of COVID-19 in the military and the entire Korean population were compared.ResultsBy August 2021, 85.60% of military personnel were fully vaccinated. During the study period, a total of 174 COVID-19 cases were confirmed in the 39 units. More local transmission (herd immunity group vs. non-herd immunity group [%], 1 [0.91] vs. 39 [60.94]) and hospitalizations (12 [11.01] vs. 13 [27.08]) occurred in the units that were not believed to have achieved herd immunity. The percentage of fully vaccinated individuals among the confirmed COVID-19 cases increased over time, possibly due to the prevalence of the delta variant. Nevertheless, the incidence rate remained lower in military units than in the general Korean population.ConclusionAfter completing mass vaccination, the incidence rates of COVID-19 infection in the military were lower than those in the national population. New cluster infections did not occur in vaccinated units, thereby suggesting that herd immunity has been achieved in these military units. Further research is needed to determine the extent to which levels of non-pharmacological intervention can be reduced in the future.     

Multi-Faceted Analysis of COVID-19 Epidemic in Korea Considering Omicron Variant: Mathematical Modeling-Based Study

BackgroundThe most recent variant of concern, omicron (B.1.1.529), has caused numerous cases worldwide including the Republic of Korea due to its fast transmission and reduced vaccine effectiveness.MethodsA mathematical model considering age-structure, vaccine, antiviral drugs, and influx of the omicron variant was developed. We estimated transmission rates among age groups using maximum likelihood estimation for the age-structured model. The impact of non-pharmaceutical interventions (NPIs; in community and border), quantified by a parameter μ in the force of infection, and vaccination were examined through a multi-faceted analysis. A theory-based endemic equilibrium study was performed to find the manageable number of cases according to omicron- and healthcare-related factors.ResultsBy fitting the model to the available data, the estimated values of μ ranged from 0.31 to 0.73, representing the intensity of NPIs such as social distancing level. If μ < 0.55 and 300,000 booster shots were administered daily from February 3, 2022, the number of severe cases was forecasted to exceed the severe bed capacity. Moreover, the number of daily cases is reduced as the timing of screening measures is delayed. If screening measure was intensified as early as November 24, 2021 and the number of overseas entrant cases was contained to 1 case per 10 days, simulations showed that the daily incidence by February 3, 2022 could have been reduced by 87%. Furthermore, we found that the incidence number in mid-December 2021 exceeded the theory-driven manageable number of daily cases.ConclusionNPIs, vaccination, and antiviral drugs influence the spread of omicron and number of severe cases in the Republic of Korea. Intensive and early screening measures during the emergence of a new variant is key in controlling the epidemic size. Using the endemic equilibrium of the model, a formula for the manageable daily cases depending on the severity rate and average length of hospital stay was derived so that the number of severe cases does not surpass the severe bed capacity.     

Evaluation of Intervention Policies for the COVID-19 Epidemic in the Seoul/Gyeonggi Region through a Model Simulation

PurposeTo evaluate the efficacy of intervention policies on coronavirus disease-19 (COVID-19) dissemination.Materials and MethodsAn 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.ResultsTwo-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.ConclusionA compromise between social distancing and school attendance policy and timely preparations for the spread of COVID-19 are required.     

Shift in Clinical Epidemiology of Human Parainfluenza Virus Type 3 and Respiratory Syncytial Virus B Infections in Korean Children Before and During the COVID-19 Pandemic: A Multicenter Retrospective Study

BackgroundParainfluenza virus type 3 (PIV3) and respiratory syncytial virus (RSV) B epidemics occurred in South Korea in late 2021. We investigated epidemiological changes of PIV3 and RSV B infections in Korean children before and during the coronavirus disease 2019 (COVID-19) pandemic.MethodsIn this multicenter retrospective study, we enrolled patients aged less than 19 years with PIV3 or RSV infection in four university hospitals from January 2018 to January 2022. Demographic and clinical data were extracted from the subject’s medical records and analyzed for each virus.ResultsA total of 652 children with PIV3 were identified including three epidemics: 216 in 2018, 260 in 2019, and 167 in 2021. Among 627 RSV B cases, 169 were identified in 2017/2018, 274 in 2019/2020, and 115 in 2021/2022. The peak circulation of PIV3 and RSV B epidemics were delayed by 6 and 2 months, respectively, in 2021, compared with those in the pre-COVID-19 period. The median age of PIV3 infections increased in 2021 (21.5 months in 2021 vs. 13.0–14.0 in 2018–2019; P < 0.001), whereas that of RSV B infections remained unchanged (3.6–4.0 months). During the COVID-19 pandemic, less frequent hospitalization rates were observed for both PIV3 and RSV B infections, but more children needed respiratory assistance for RSV B infection in 2021/2022 epidemic (32.5%) than before (14.7–19.4%, P = 0.014).ConclusionWe observed changes in the epidemiology and clinical presentation of PIV3 and RSV B infections in Korean children during the COVID-19 pandemic.     

Coronavirus Disease 2019 Cases at Universities and Colleges in Seoul Metropolitan Area

BackgroundTo facilitate evidence-based policy-making on safe reopening of higher education facilities, there is an urgent need to assess baseline profile of coronavirus disease 2019 (COVID-19) incidents within the university/college settings. We aimed to describe the epidemiology of COVID-19 in universities/colleges in Seoul Metropolitan Area during COVID-19 pandemic period.MethodsAmong the 38 universities in Seoul, 23 have agreed to participate in the study. Confirmed COVID-19 cases were identified from individual-level case reports submitted to the universities and to the health authorities from February 1, 2020, to June 30, 2021. Through the linkage with the Central Disease Control Headquarters'' database, number of secondary infected cases (both within and outside of the campus) were counted.ResultsBetween February 2020 and June 2021, a total of 827 COVID-19 cases were confirmed and reported in the universities across Seoul Metropolitan City. Generally, the community-associated cases had peaks preceding the university/college-associated. Of those with the documented clinical parameters, 38.6% of the cases were asymptomatic. Among them, 93% were potentially exposed off-campus, and 87.7% of the cases had not produced the secondary infection cases.ConclusionIn the setting of rigorous infection prevention measures in combination with on- and off- hybrid classes, COVID-19 incidences and outbreaks were limited in university and college campus area across Seoul Metropolitan Area. The evidence around the infection preventive measures in higher education facilities in Seoul Metropolitan Area, suggest insignificant impact on community transmission.     

Recent insights into SARS-CoV-2 omicron variant

The SARS-CoV-2 omicron variant (B.1.1.529) was first identified in Botswana and South Africa, and its emergence has been associated with a steep increase in the number of SARS-CoV-2 infections. The omicron variant has subsequently spread very rapidly across the world, resulting in the World Health Organization classification as a variant of concern on 26 November 2021. Since its emergence, great efforts have been made by research groups around the world that have rapidly responded to fill our gaps in knowledge for this novel variant. A growing body of data has demonstrated that the omicron variant shows high transmissibility, robust binding to human angiotensin-converting enzyme 2 receptor, attenuated viral replication, and causes less severe disease in COVID-19 patients. Further, the variant has high environmental stability, high resistance against most therapeutic antibodies, and partial escape neutralisation by antibodies from convalescent patients or vaccinated individuals. With the pandemic ongoing, there is a need for the distillation of literature from primary research into an accessible format for the community. In this review, we summarise the key discoveries related to the SARS-CoV-2 omicron variant, highlighting the gaps in knowledge that guide the field's ongoing and future work.     

Analysis of PubMed and KoreaMed Indexed Korean Publications on COVID-19

During the coronavirus disease 2019 (COVID-19) pandemic, publications on the disease have exploded globally. The present study analyzed PubMed and KoreaMed indexed COVID-19 publications by Korean researchers from January 1, 2020 to August 19, 2021. A total of 83,549 COVID-19 articles were recorded in PubMed and 1,875 of these were published by Korean authors in 673 journals (67 Korean and 606 overseas journals). The KoreaMed platform covered 766 articles on COVID-19, including 612 by Korean authors. Among the Journal of Korean Medical Science (JKMS) articles on COVID-19, PubMed covered 176 and KoreaMed 141 documents. Korean researchers contributed to 2.2% of global publications on COVID-19 in PubMed. The JKMS has published most articles on COVID-19 in Korea.     

Short Term Impact of Coronavirus Disease 2019 Vaccination in Children in Korea

BackgroundThe epidemiology of coronavirus disease 2019 (COVID-19) has changed continuously throughout the pandemic.MethodsWe analyzed changes in the incidence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection according to the age group in South Korea from February 2020 to December 2021.ResultsSince the COVID-19 pandemic, the incidence among adults aged ≥ 18 years was higher than all the other age groups in 2020; however, a shift toward younger ages occurred in June 2021. In addition, we found significant changes in epidemiology after the introduction of SARS-CoV-2 vaccines in adults aged ≥ 18 and children 12–17 years. Until recently, children were not regarded as the drive for the pandemic; however, children aged 5–11 and 0–4 years had the highest incidence among all the age groups.ConclusionTherefore, policies for clinical support for an increase in COVID-19 cases among young children and age-specific preventive measures are needed.     

A new SARS-CoV-2 variant with high lethality poorly detected by RT-PCR on nasopharyngeal samples: an observational study

ObjectivesIn early January 2021 an outbreak of nosocomial cases of coronavirus disease 2019 (COVID-19) emerged in Western France; RT-PCR tests were repeatedly negative on nasopharyngeal samples but positive on lower respiratory tract samples. Whole-genome sequencing (WGS) revealed a new variant, currently defining a novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lineage B.1.616. In March, the WHO classified this as a ‘variant under investigation’ (VUI). We analysed the characteristics and outcomes of COVID-19 cases related to this new variant.MethodsClinical, virological, and radiological data were retrospectively collected from medical charts in the two hospitals involved. We enrolled those inpatients with: (a) positive SARS-CoV-2 RT-PCR on a respiratory sample, (b) seroconversion with anti-SARS-CoV-2 IgG/IgM, or (c) suggestive symptoms and typical features of COVID-19 on a chest CT scan. Cases were categorized as B.1.616, a variant of concern (VOC), or unknown.ResultsFrom 1st January to 24th March 2021, 114 patients fulfilled the inclusion criteria: B.1.616 (n = 39), VOC (n = 32), and unknown (n = 43). B.1.616-related cases were older than VOC-related cases (81 years, interquartile range (IQR) 73–88 versus 73 years, IQR 67–82, p < 0.05) and their first RT-PCR tests were rarely positive (6/39, 15% versus 31/32, 97%, p < 0.05). The B.1.616 variant was independently associated with severe disease (multivariable Cox model HR 4.0, 95%CI 1.5–10.9) and increased lethality (28-day mortality 18/39 (46%) for B.1.616 versus 5/32 (16%) for VOC, p = 0.006).ConclusionWe report a nosocomial outbreak of COVID-19 cases related to a new variant, B.1.616, which is poorly detected by RT-PCR on nasopharyngeal samples and is associated with high lethality.     

Clinical Features of Adult COVID-19 Patients without Risk Factors before and after the Nationwide SARS-CoV-2 B.1.617.2 (Delta)-variant Outbreak in Korea: Experience from Gyeongsangnam-do

BackgroundData on severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) delta variant virulence are insufficient. We retrospectively compared the clinical features of adult coronavirus disease 2019 (COVID-19) patients without risk factors for severe COVID-19 who entered residential treatment centers (RTCs) before and after the delta variant outbreak.MethodsWe collected medical information from two RTCs in South Korea. On the basis of nationwide delta variant surveillance, we divided the patients into two groups: 1) the delta-minor group (diagnosed from December 2020–June 2021, detection rate < 10%) and 2) the delta-dominant group (diagnosed during August 2021, detection rate > 90%). After propensity-score matching, the incidences of pneumonia, hospital transfer and need for supplemental oxygen were compared between the groups. In addition, risk factors for hospital transfer were analysed.ResultsA total of 1,915 patients were included. The incidence of pneumonia (14.6% vs. 9.2%, P = 0.009), all-cause hospital transfer (10.4% vs. 6.3%, P = 0.020) and COVID-19-related hospital transfer (7.5% vs. 4.8%, P = 0.081) were higher in the delta-dominant group than those in the delta-minor group. In the multivariate analysis, the delta-dominant group was an independent risk factor for all-cause (adjusted odds ratio [aOR], 1.91; 95% confidence interval [CI], 1.16–3.13; P = 0.011) and COVID-19-related hospital transfer (aOR, 1.86; 95% CI, 1.04–3.32; P = 0.036).ConclusionHospitalization rates were increased in the adult COVID-19 patients during the delta variant nationwide outbreak. Our results showed that the delta variant may be more virulent than previous lineages.     

One Year Follow-Up of COVID-19 Related Symptoms and Patient Quality of Life: A Prospective Cohort Study

PurposeGlobally, concerns have grown regarding the long-term effects of novel coronavirus disease (COVID-19) infection. Therefore, we evaluated the long-term course of persistent symptoms and patient quality of life.Materials and MethodsThis prospective cohort study was conducted at a single tertiary university hospital from August 31, 2020 to March 29, 2021 with adult patients followed at 6 and 12 months after acute COVID-19 symptom onset or diagnosis. Clinical characteristics, self-reported symptoms, EuroQol 5 dimension 5 level (EQ5D-5L) index scores, Korean version of the Patient Health Questionnaire-9 (PHQ-9), Korean version of the Posttraumatic Stress Disorder Checklist-5 (PCL-5-K), and Generalized Anxiety Disorder-7 (GAD-7) were investigated. Symptom persistent or non-persistent groups were defined according to persistency of COVID-19 related symptoms or signs after acute COVID-19 infection, respectively.ResultsOf all 235 patients, 170 (64.6%) patients were eligible for analysis. The median age was 51 (interquartile range, 37–61) years old, and 102 patients were female (60.0%). After 12 months from acute COVID-19 infection, in total, 83 (48.8%) patients still suffered from COVID-19-related symptoms. The most common symptoms included amnesia (24.1%), insomnia (14.7%), fatigue (13.5%), and anxiety (12.9%). Among the five EQ5D-5L categories, the average value of anxiety or depression was the most predominant. PHQ-9 and PCL-5-K scores were statistically higher in the COVID-19–related symptom persistent group than the non-persistent group (p=0.001). However, GAD-7 scores showed no statistical differences between the two groups (p=0.051).ConclusionNeuropsychiatric symptoms were the major COVID-19–related symptoms after 12 months from acute COVID-19 infection, reducing quality of life.     

Impact of the Coronavirus Disease 2019 (COVID-19) Pandemic on Medical Use of Military Hospitals in Korea

BackgroundThe coronavirus disease 2019 (COVID-19) pandemic began in December 2019. While it has not yet ended, COVID-19 has already created transitions in health care, one of which is a decrease in medical use for health-related issues other than COVID-19 infection. Korean soldiers are relatively homogeneous in terms of age and physical condition. They show a similar disease distribution pattern every year and are directly affected by changes in government attempts to control COVID-19 with nonpharmaceutical interventions. This study aimed to identify the changes in patterns of outpatient visits and admissions to military hospitals for a range of disease types during a pandemic.MethodsOutpatient attendance and admission data from all military hospitals in South Korea from January 2016 to December 2020 were analyzed. Only active enlisted soldiers aged 18–32 years were included. Outpatient visits where there was a diagnosis of pneumonia, acute upper respiratory tract infection, infectious conjunctivitis, infectious enteritis, asthma, allergic rhinitis, allergic conjunctivitis, atopic dermatitis, urticaria, and fractures were analyzed. Admissions for pneumonia, acute enteritis, and fractures were also analyzed. All outpatient visits and admissions in 2020 for each disease were counted on a weekly basis and compared with the average number of visits over the same period of each year from 2016 to 2019. The corrected value was calculated by dividing the ratio of total weekly number of outpatient visits or admissions to the corresponding medical department in 2020 to the average in 2016–2019.ResultsA total of 5,813,304 cases of outpatient care and 143,022 cases of admission were analyzed. For pneumonia, the observed and corrected numbers of outpatient visits and admissions in 2020 decreased significantly compared with the average of other years (P < 0.001). The results were similar for outpatient visits for acute upper respiratory tract infection and infectious conjunctivitis (P < 0.001), while the corrected number of outpatient visits for infectious enteritis showed a significant increase in 2020 (P = 0.005). The corrected number of outpatient visits for asthma in 2020 did not differ from the average of the previous 4 years but the number of visits for the other allergic diseases increased significantly (P < 0.001). For fractures, the observed and corrected numbers of outpatient visits and admissions in 2020 decreased significantly compared with the average of other years (P < 0.001).ConclusionDuring the COVID-19 pandemic, outpatient visits to military hospitals for respiratory and conjunctival infections and fractures decreased, whereas visits for allergic diseases did not change or increased only slightly. Admissions for pneumonia decreased significantly in 2020, while those for acute enteritis and fractures also decreased, but showed an increased proportion compared with previous years. These results are important because they illustrate the changing patterns in lifestyle as a result of public encouragement to adopt nonpharmaceutical interventions during the pandemic and their effect on medical needs for both infectious and noninfectious diseases in a select group.     

Relevance of immune response and vaccination strategies of SARS-CoV-2 in the phase of viral red queen dynamics

BackgroundFollowing a relatively mild first wave of coronavirus disease 2019 (COVID-19) in India, a deadly second wave of the pandemic overwhelmed the healthcare system due to the emergence of fast-transmitting SARS-CoV-2 genetic variants. The emergence and spread of the B.1.617.2/Delta variant considered to be driving the devastating second wave of COVID-19 in India. Currently, the Delta variant has rapidly overtaken the previously circulating variants to become the dominant strain. Critical mutations in the spike/RBD region of these variants have raised serious concerns about the virus's increased transmissibility and decreased vaccine effectiveness. As a result, significant scientific and public concern has been expressed about the impact of virus variants on COVID-19 vaccines.ObjectivesThe purpose of this article is to provide an additional explanation in the context of the evolutionary trajectory of SARS-CoV-2 variants in India, the vaccine-induced immune response to the variants of concern (VOC), and various vaccine deployment strategies to rapidly increase population immunity.ContentPhylogenetic analysis of SARS-CoV-2 isolates circulating in India suggests the emergence and spread of B.1.617 variant. The immunogenicity of currently approved vaccines indicates that the majority of vaccines elicit an antibody response and some level of protection. According to current data, vaccines in the pre-fusion configuration (2p substitution) have an advantage in terms of nAb titer, but the duration of vaccine-induced immunity, as well as the role of T cells and memory B cells in protection, remain unknown. Since vaccine efficacy on virus variants is one of the major factors to be considered for achieving herd immunity, existing vaccines need to be improved or effective next-generation vaccines should be developed to cover the new variants of the virus.     

Comparing COVID-19 vaccines for their characteristics,efficacy and effectiveness against SARS-CoV-2 and variants of concern: a narrative review

BackgroundVaccines are critical cost-effective tools to control the coronavirus disease 2019 (COVID-19) pandemic. However, the emergence of variants of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may threaten the global impact of mass vaccination campaigns.AimsThe objective of this study was to provide an up-to-date comparative analysis of the characteristics, adverse events, efficacy, effectiveness and impact of the variants of concern for 19 COVID-19 vaccines.SourcesReferences for this review were identified through searches of PubMed, Google Scholar, BioRxiv, MedRxiv, regulatory drug agencies and pharmaceutical companies' websites up to 22nd September 2021.ContentOverall, all COVID-19 vaccines had a high efficacy against the original strain and the variants of concern, and were well tolerated. BNT162b2, mRNA-1273 and Sputnik V after two doses had the highest efficacy (>90%) in preventing symptomatic cases in phase III trials. mRNA vaccines, AZD1222, and CoronaVac were effective in preventing symptomatic COVID-19 and severe infections against Alpha, Beta, Gamma or Delta variants. Regarding observational real-life data, full immunization with mRNA vaccines and AZD1222 seems to effectively prevent SARS-CoV-2 infection against the original strain and Alpha and Beta variants but with reduced effectiveness against the Delta strain. A decline in infection protection was observed at 6 months for BNT162b2 and AZD1222. Serious adverse event rates were rare for mRNA vaccines—anaphylaxis 2.5–4.7 cases per million doses, myocarditis 3.5 cases per million doses—and were similarly rare for all other vaccines. Prices for the different vaccines varied from $2.15 to $29.75 per dose.ImplicationsAll vaccines appear to be safe and effective tools to prevent severe COVID-19, hospitalization, and death against all variants of concern, but the quality of evidence greatly varies depending on the vaccines considered. Questions remain regarding a booster dose and waning immunity, the duration of immunity, and heterologous vaccination. The benefits of COVID-19 vaccination outweigh the risks, despite rare serious adverse effects.     

Epidemiological Features of 105 Patients Infected with the COVID-19

ObjectiveTo investigate and evaluate the clinical features of patients infected with the 2019 novel coronavirus (COVID-19) outside of Wuhan.Methods105 patients admitted to our hospital with clinical- and laboratory-confirmed COVID-19 infection were studied. Data were collected from January 17, 2020 to March 5, 2020.Results105 patients (57 male and 48 female) were confirmed to have COVID-19 infection. Among the 105 patients, 55 (52%) had made short trips to Wuhan during the two weeks before the onset of illness, and these were the first-generation confirmed cases. An exact date of close contact with someone in Wenzhou with confirmed or suspected COVID-19 infection from Wuhan (the second-generation confirmed cases) could be provided by 38 (36%) patients. Of the remaining patients, six (6%; the third-generation confirmed cases) were familial clusters of the second-generation confirmed cases, three (3%) had no definite epidemiological features, and 16 (15%) were from the same location as for the case report.ConclusionDue to the infectiousness of COVID-19, patients with infections should be diagnosed and treated as early as possible after developing fever symptoms or showing other clinical characteristics or imaging features. With respect to high-risk cases, we must focus on any complications that arise and take effective measures to treat them immediately. This will significantly improve the prognosis of patients with severe infections.     

Analysis of the Impact of the Coronavirus Disease Epidemic on the Emergency Medical System in South Korea Using the Korean Triage and Acuity Scale

PurposeSevere acute respiratory syndrome coronavirus 2, which causes coronavirus disease 2019 (COVID-19), has spread worldwide. Global health systems, including emergency medical systems, are suffering from a lack of medical resources. Using a method for classifying patients visiting the emergency department (ED), we aimed to investigate trends in emergency medical system usage during the COVID-19 epidemic in Korea.Materials and MethodsThis retrospective observational study included patients who visited emergency medical institutions registered with the National Emergency Department Information System database from January 1, 2017 to May 31, 2020. The primary outcome was identification of changes in the distribution of patients visiting the ED according to the type of emergency medical institution. The secondary outcome was a detailed comparison of Korean Triage and Acuity Scale (KTAS) levels and patient distributions before and during the infectious disaster crisis period.ResultsSevere patients visited regional emergency centers (RECs) and local emergency centers (LECs) more frequently during the COVID-19 period, and disposition status warranting admission to the intensive care unit or resulting in death was more common in RECs and LECs during the COVID-19 period [RECs, before COVID-19: 300686 (6.3%), during COVID-19: 33548 (8.0%) (p<0.001); LECs, before COVID-19: 373593 (3.7%), during COVID-19: 38873 (4.5%) (p<0.001)].ConclusionDuring the COVID-19 period, severe patients were shifted to advanced emergency medical institutions, and the KTAS better reflected severe patients. Patient distribution according to the stage of emergency medical institution improved, and validation of the KTAS triage increased more in RECs.     

Prevalence of SARS-CoV-2 Antibody in 2,935 Healthcare Workers at 6 Major Hospitals,Daegu, Korea

BackgroundIn Korea, the first community outbreak of coronavirus disease 2019 (COVID-19) occurred in Daegu on February 18, 2020. This study was performed to investigate the prevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies in healthcare workers (HCWs) at 6 major hospitals in Daegu.MethodsBlood specimens of 2,935 HCWs at 6 major hospitals in Daegu from January 2021 to February 2021 were collected. Every specimen was tested for antibody against SARS-CoV-2 using both Elecsys Anti-SARS-CoV-2 electrochemiluminescence immunoassay (Roche Diagnostics, Rotkreuz, Switzerland) and R-FIND COVID-19 IgG/M/A enzyme-linked immunosorbent assay kit (SG medical Inc., Seoul, Korea) as screening tests. If 1 or more of these screening test results was positive, 2 additional antibody tests were performed using Abbott Anti-SARS-CoV-2 IgG assay (Abbott, Abbott Park, IL, USA) and cPass SARS-CoV-2 Neutralization Antibody Detection Kit (GenScript USA Inc., Piscataway, NJ, USA). If 2 or more of the total 4 test results were positive, it was determined as positive for the antibody against SARS-CoV-2.ResultsAccording to the criteria of SARS-CoV-2 antibody positivity determination, 12 subjects were determined as positive. The overall positive rate of the SARS-CoV-2 antibody was 0.41% (12/2,935). Of the 12 subjects determined as positive, 7 were diagnosed with COVID-19, and the remaining 5 were nondiagnosed cases of COVID-19.ConclusionIn early 2021, the overall seroprevalence of SARS-CoV-2 antibody among HCW located in Daegu was 0.41%, and 0.17% excluding COVID-19 confirmed subjects. These results were not particularly high compared with the general public and were much lower than HCWs in other countries.